Candles burn next to a lighted tree at a makeshift shrine in Newtown, Connecticut, commemorating the victims of the mass shooting at Sandy Hook Elementary School on December 14, 2012.
Erica Simmons rings the campus bell at Agnes Scott College in Decatur, Georgia, during a nationwide commemoration December 21, marking a week since the Newtown, Connecticut, mass shooting. Church bells rang out across the country at 9:30 ET Friday to remember those who died in the gun rampage.
A woman pauses at a streetside memorial during a moment of silence on December 21 in Newtown.
Connecticut State Police block the road to Sandy Hook Elementary School during a moment of silence on December 21. A week ago, a gunman forced his way into the school and shot and killed 26 people, including 20 children.
A woman bows her head in Newtown's Sandy Hook village on December 21.
People observe a moment of silence for the school shooting victims at the Blue Colony Diner in Newtown on December 21.
Children in Newtown, excluding Sandy Hook Elementary, return to classes on Tuesday, December 18, four days after the shooting at the elementary school.
U.S. Rep. David Cicilline, D-Rhode Island, holds a news conference with the Brady Campaign to discuss gun violence. In attendance with the Brady Campaign were several survivors of gun violence and family members of victims of gun violence.
Members of the human rights group Volunteers Against Crime and Corruption light candles showing the names of those killed during the shooting at Sandy Hook Elementary School, during a prayer vigil in front of the U.S. Embassy in Manila, Philippines on December 18.
Children light candles to pay their respects to the victims of the Newtown, Connecticut, shooting at the main square in Tirana, Albania, on Monday, December 17. The deadly gun rampage at Sandy Hook Elementary School has provoked strong reactions from around the world.
Protesters march on the National Rifle Association's Capitol Hill lobbyist offices in Washington on December 17.
New York Mayor Michael Bloomberg speaks out for stronger gun control at a press conference at City Hall on December 17. Bloomberg, co-chair of Mayors Against Illegal Guns, was joined by victims and survivors of gun violence.
Chris Foye, whose son Chris Owens was killed by a stray bullet in 2009, stands with other survivors and family members of gun violence at Bloomberg's press conference on December 17 in New York.
People pay their respects on December 17 at a makeshift shrine in Newtown to the victims of Friday's elementary school shooting. Funerals began Monday in the Connecticut town.
Traders on the floor of the New York Stock Exchange hold a moment of silence on December 17 in honor of the shooting victims.
Young people mourn at Newtown High School before a memorial service attended by President Obama on Sunday, December 16.
President Barack Obama waits to speak at an interfaith vigil for the shooting victims from Sandy Hook Elementary School December 16 at Newtown High School.
Mourners comfort one another December 16 before U.S. President Barack Obama speaks at an interfaith vigil for the shooting victims.
Two women embrace before the interfaith vigil at Newtown High School on Sunday evening.
From left: Newtown residents Claire Swanson, Kate Suba, Jaden Albrecht, Simran Chand and New London, Connecticut, residents Rachel Pullen and her son, Landon DeCecco, hold candles at a memorial for victims on Sunday, December 16, in Newtown, Connecticut.
A young boy walks past Christmas trees set up at a makeshift shrine to the shooting victims in Newtown, Connecticut, on December 16.
Ty Diaz is kissed by his mother, Yvette, at a memorial down the street from Sandy Hook on December 16.
Teddy bears, flowers and candles in memory of those killed are left at a memorial down the street from the school on December 16.
Two teenagers embrace at a makeshift shrine to the victims in Newtown on December 16.
Nuns pay their respects at a makeshift shrine to the victims on December 16.
Members of Sisters of Christian Charity go to lay flowers in front of the Sandy Hook Elementary School on December 16 in Newtown.
A woman receives a hug as she leaves morning service December 16 at Trinity Church in Newtown near the elementary school.
Parishioners pay their respects to the victims of the elementary school shooting while attending Mass at St. Rose of Lima Roman Catholic Church in Newtown on December 16.
Police officers honor the victims of the school shooting at the St. Rose of Lima Roman Catholic Church on December 16 in Newtown.
The Jacksonville Jaguars have a moment of silence in honor of the Sandy Hook Elementary School shooting victims before their game against the Miami Dolphins on December 16.
A parishioner kneels in front of a makeshift memorial at St. Rose of Lima Roman Catholic Church in Newtown on December 16.
A police officer removes flowers from a busy intersection on December 16 in Newtown. Police said they were afraid the memorial, left for the victims of the Sandy Hook Elementary School shooting, would cause a traffic hazard.
A woman hugs her daughter on the steps of Trinity Church on December 16 in Newtown.
Angel wood cutouts for each of the 27 victims are set up on hillside in Newtown on December 16.
People in Bangalore, India, hold cards and photographs of the slain at a candlelight vigil outside a Catholic church on December 16.
J.J. Watt of the Houston Texans shows his glove in remembrance of the victims before the start of a game against the Indianapolis Colts on December 16 in Houston.
Donna Soto, right, mother of Victoria Soto, the first-grade teacher at Sandy Hook Elementary School who was shot and killed while protecting her students, hugs her daughter Karly while mourning their loss at a candlelight memorial at Stratford High School on Saturday, December 15, in Stratford, Connecticut.
Firefighters kneel to pay their respects at a makeshift memorial near the school in Newtown on Saturday.
A child lights a candle at a memorial filled with flowers, stuffed toys and candles outside of Saint Rose of Lima Church near Sandy Hook Elementary School in Newtown, Connecticut on Saturday.
Candles light up a memorial outside of Saint Rose of Lima Church in Newtown.
Lucas, Kelly and Michael DaSilva pray and embrace at a makeshift memorial near the school in Newtown.
People are overcome with emotion Saturday at a makeshift memorial near Sandy Hook Elementary School in Newtown.
Residents arrive Saturday to pay tribute to the victims of an elementary school shooting in Newtown, Connecticut.
A couple carry balloons to place at a curbside shrine to in Newtown on Saturday.
A mother and daughter attend a prayer service at St. John's Episcopal Church in Newtown on Saturday.
Flowers and signs of sympathy adorn the street leading to Sandy Hook Elementary School.
Claudia Urbiana and daughter Jocelyne Cardenas, left, hug outside of the entrance to the Sandy Hook school.
A makeshift memorial with flowers, stuffed toys and candles sit outside Saint Rose of Lima Roman Catholic Church in Newtown, Connecticut, on Saturday.
A man bows his head as he stands at a makeshift memorial, outside Saint Rose of Lima Roman Catholic Church in Newtown on Saturday, December 15.
New Jersey resident Steve Wruble, who was moved to drive out to Connecticut to support local residents, grieves for victims at the entrance to Sandy Hook village in Newtown on Saturday.
People attend a prayer service in Newtown on Saturday to reflect.
A mother hugs her children after paying tribute to the victims in Newtown on Saturday, December 15.
Newtown High School student Trevor Lopez stands outside of a church where residents have come to pray and reflect on Saturday
Andrea Jaeger places flowers and a candle at a makeshift memorial outside a firehouse near Sandy Hook Elementary School on Saturday.
The U.S. flag flies at half-staff above the White House on Saturday.
Ken Kowalsky and his daughter Rebecca, 13, embrace while standing at the end of the road leading to Sandy Hook Elementary School on Saturday.
A woman puts a flower near crosses planted by Rio de Paz (Rio of Peace), in memory of the victims of the Sandy Hook Elementary school shooting on Copacabana beach in Rio de Janeiro on Saturday.
A woman sits during a service at the Asylum Hill Congregational Church in Hartford, Connecticut on Friday, December 14.
Fans at the NBA game between the Utah Jazz and the Phoenix Suns participate in a moment of silence for the victims of the Newtown shooting on Friday in Phoenix.
An overflow crowd listens to a church service held at the St. Rose of Lima Catholic Church in Newtown on December 14.
People gather for a prayer vigil at St. Rose Church on Friday.
People gather for a vigil outside the White House in Washington following the Connecticut elementary school shooting on Friday.
Candles burn as people gather for a vigil outside the White House.
Hartford, Connecticut, Mayor Padro Segarra speaks emotionally about the students and teachers who died earlier in the day at Sandy Hook Elementary School in nearby Newtown at a candlelight vigil at Bushnell Park in Hartford on Friday.
Cynthia Alvarez is comforted by her mother, Lilia, as people gather for a prayer vigil at St. Rose of Lima Roman Catholic Church in Newtown.
People gather for a prayer vigil at St. Rose Church in Newtown.
People gather for a prayer vigil at St. Rose Church.
People gather inside the St. Rose Church to remember the shooting victims on Friday
A woman bows her head during a vigil for the shooting victims at St. Rose Church.
People gather in the St. Rose Church for a memorial service Friday.
Women comfort each other during the vigil at St. Rose Church.
A woman looks on during the vigil at St. Rose Church.
People hug outside of the Newtown United Methodist Church on Friday, near the site of the shootings at the Sandy Hook school.
A flag at the U.S. Capitol flies at half-staff after President Barack Obama ordered the action while speaking from the White House. Obama called for "meaningful action" in the wake of the school shooting.
Julie Henson of San Francisco joins other people outside the White House to participate in a candlelight vigil on Friday.
Obama wipes tears as he makes a statement in response to the shooting on Friday.
Washington resident Rachel Perrone, left, and her 5-year-old son, Joe, center, join others outside the White House in a candlelight vigil.
Faisal Ali, right, of Colorado Springs, Colorado, joins the vigil outside the White House.
People gather outside the White House to participate in a candlelight vigil.
Supporters of gun control hold a candlelight vigil for victims of the shooting outside the White House.
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
Reaction to Newtown school killings
STORY HIGHLIGHTS
- NEW: "These tragedies must end. And to end them, we must change," Obama says
- NEW: He vows action, saying America must do more to protect its children
- NEW: The mother of a teacher being hailed as a hero calls her daughter "selfless"
- All victims at the Sandy Hook school were shot multiple times, a medical examiner says
Newtown, Connecticut (CNN) -- "We can't tolerate this anymore."
That's what President Barack Obama told those attending a memorial service Sunday in Newtown, Connecticut, two days after a man shot his way into Sandy Hook Elementary School and killed 26 people -- 20 of them children no older than 7, who would never go on a date, drive a car, marry or have kids of their own.
Obama offered his condolences, saying, "All across this land of ours, we have wept with you." He praised the residents of Newtown for having pulled together and "loved one another" with a spirit all could emulate. And he asked whether more could be done to prevent more parents, sisters and brothers, like those in this quiet New England town, from suffering similar heartaches.
"Can we honestly say we're doing enough to keep our children -- all of them -- safe from harm?" Obama said, adding that "if we don't get that right, we don't get anything right."
"If we're honest with ourselves, the answer is no."
Read the full text of the president's speech
His call to action capped an emotional prayer service at Newtown High School, in which local leaders of several religions -- a Jewish rabbi singing a prayer, a Muslim man choking back tears, and several Christian leaders offering perspective -- attempted to comfort a shattered community. Nine hundred watched in the school's auditorium, including several children toting teddy bears, and another 1,300 saw the proceedings from a nearby overflow room.
The aim was to show those suffering in Newtown they were not alone. With the help of their neighbors, they could move past this "act of unfathomable violence and destruction," explained the Rev. Matt Crebbin, senior minister at Newtown Congregational Church.
"We needed this," Crebbin said of the service. "We needed to be together."
Remembering the victims
That sentiment was echoed by Obama, who said the nation stands with Newtown. Then he went further than that, saying that the country owes it to them -- and to the people of Tuscon, Arizona; Oak Creek, Wisconsin; Aurora, Colorado, communities that also have been sites of mass shootings in the last two years -- not just to remember the victims, but take steps to prevent more bloodshed in the future.
The president didn't specify what steps he favors, but he did promise to put the power of his office toward preventing more senseless grief -- saying, "We can't accept events like this as routine."
"These tragedies must end. And to end them, we must change."
Analysis: Why gun controls are off the agenda in America
Clearer picture of what happened, but not why
The first calls came into police around 9:30 a.m. Friday.
Adam Lanza used "an assault weapon" to "literally (shoot) an entrance into the building," Connecticut Gov. Dannel Malloy said Sunday. The nightmare got worse as he moved through Sandy Hook's halls.
Timeline of the shooting
Using a Bushmaster AR-15 "assault-type rifle," the 20-year-old fired "multiple magazines" -- each of which contained 30 bullets -- to gun down six adults and children in two classrooms, said Connecticut State Police Lt. J. Paul Vance. He then took out a handgun and shot himself in a classroom as law enforcement officers approached, officials said.
All the victims were shot multiple times, said H. Wayne Carver II, Connecticut's chief medical examiner. Their deaths -- as well as that of Nancy Lanza, Adam's mother who suffered "multiple gunshot wounds" at their Newtown home -- are classified as homicides.
"This probably is the worst I have seen or the worst that I know of any of my colleagues having seen," said Carver, who did autopsies on seven victims.
Why did Lanza do it? That much, at least publicly, remains a mystery.
He had no criminal record. He and his mother, who collected guns, had visited a gun range at least once, ATF spokeswoman Ginger Colbrun said.
The few who spoke of Lanza publicly, including an aunt and former classmate, described him as very intelligent and quiet.
His father, Peter Lanza, released a statement Saturday saying his family is "grieving along with all those who have been affected by this enormous tragedy."
"We are in a state of disbelief and trying to find whatever answers we can," the father said.
Authorities shared that sentiment. Even as they have offered more details on what happened Friday morning, they haven't given a motive.
"We will and we are searching diligently and nonstop to attempt to answer that," said Vance, the police spokesman.
Tears and hope
At Sunday's memorial service, Obama solemnly read out the first names of those Lanza killed.
"God has called them all home," he said.
Share your tributes
And for every victim, there's a story.
Six-year-old Emilie Parker was "bright, creative and very loving," her father, Robbie Parker, recalled Saturday.
"My daugher Emilie would be one of the first ones to be standing up and giving her love and support to all of those victims, because that is the type of person she is," he said. "...This world is a better place because she has been in it."
Victoria Soto, 27, moved her students away from her first-grade classroom door when she heard gunfire. She is being hailed for having saved some of her students, even though she herself didn't survive.
"She was truly selfless," her mother Donna Soto said Sunday. "She would not hesitate to think to save anyone else before herself and especially children. She loved them more than life."
Many more tears will be shed in the coming days, as victims are laid to rest.
The first two funerals tied to the massacre -- for Noah Pozner and Jack Pinto, both Sandy Hook students -- will begin Monday at noon and 1 p.m. respectively, according to the Connecticut Funeral Directors Association.
Malloy, Connecticut's governor, said Sunday that they will never be forgotten. At the same time, he expressed hope that the strength of community will make a difference.
"We will go on. We will find strength," he said at Sunday's memorial service. "We will get better."
What really makes schools safer?
School shooting: Shattering the sense of safety
10 ways to put brakes on mass shootings in schools
CNN's Susan Candiotti reported from Newtown, Connecticut, and Greg Botelho reported from Atlanta. CNN's David Ariosto, Candy Crowley, Dana Ford, Catherine E. Shoichet, Ashleigh Banfield, Joe Johns, Terry Frieden, Michael Martinez and Chuck Johnston contributed to this report.