(CNN) -- Those who have survived a devastating tornado in Joplin, Missouri, should do their utmost to live up to the example set by those who died while helping others escape the storm, President Barack Obama said Sunday at a memorial service for the victims.
Obama spoke about two of the heroes from the twister, which barreled into Joplin packing 200-mph winds a week ago Sunday.
One of them, Dean Wells, directed his co-workers and customers at Home Depot to safety, returning again and again for more people until a wall of the store fell on top of him, the president said.
And Christopher Lucas, 26, a manager at a Pizza Hut, herded employees and customers into a walk-in freezer, finding a bungee cord to hold the door shut from the inside and wrapping the other end around his arm. Lucas held on as long as he could, Obama told the crowd Sunday, "until he was pulled away by the incredible force of the storm. He died saving more than a dozen people in that freezer.
"There are heroes around us all the time," the president said. "And so, in the wake of this tragedy, let us live up to their example, to make each day count, to live with a sense of mutual regard, to live with that same compassion that they demonstrated in their final hours. We are called by them to do everything we can to be worthy of this chance we've been given to carry on."
The tornado swept a 13-mile path, the National Weather Service said Sunday, raising its earlier estimate of six miles.
It destroyed neighborhoods, stripped the bark from trees, reduced homes in its path to unrecognizable rubble and killed more people than any other U.S. tornado since modern recordkeeping began in 1950. Early Sunday morning, Joplin City Manager Mark Rohr told CNN the death toll was 142. State officials have released the names of 87 victims.
Authorities have 146 sets of human remains, Andrea Spillars, deputy director of the Missouri Department of Public Safety, said Sunday. Some of the remains may belong to the same person, she said, cautioning the figure should not be considered a death toll at this point.
"It seems inconceivable that just one week ago, the people of Joplin were going about their daily lives, doing the ordinary things that people do on a Sunday evening -- cooking dinner, watching TV, walking the dog, attending their sons' and daughters' graduation," said Missouri Gov. Jay Nixon, who spoke before Obama at the memorial service.
"This tragedy has changed us forever," Nixon said. "This community will never be the same. We will never be the same ... but those we love, those we lost, are safe with God and safe in our hearts. And in our hearts the joy they gave us lives on and nothing can take that from us. We can and we will heal ... by God's grace, we will restore this community and by God's grace we will renew our souls."
Earlier, the Rev. Aaron Brown told those present, "I think God is saying to you right now, death doesn't get the last word. Death doesn't win ... Life wins."
He challenged survivors to live out the legacy of those who died. "They may have lost their lives, but none of them would want you to stop living yours," he said.
Obama noted how the people of Joplin pulled together in the immediate aftermath of the storm, as residents transported the injured to hospitals on doors in the back of pickup trucks, businesses filled trucks with donations and restaurants helped to feed people in need.
"You have shown the world what it means to love thy neighbor," Obama said. "You've banded together ... you've demonstrated a simple truth: That amid heartbreak and tragedy, no one is a stranger. Everybody is a brother. Everybody is a sister. We can all love one another."
He pledged the nation will stand with the people of Joplin as they rebuild. "Your country will be with you every step of the way," he said to cheers and applause. "We will be with you every step of the way. We're not going anywhere. The cameras may leave, the spotlight may shift, but we will be with you every step of the way until Joplin is restored and this community is back on its feet."
It was the third time in a month Obama visited a community savaged by a terrible act of nature to comfort survivors and talk with local leaders about rebuilding.
As Obama toured the storm damage, a few hundred people waved to him along his motorcade route, waving flags and snapping pictures. A few held signs saying, "God Bless Joplin."
The number of those unaccounted for has dropped to 43, Spillars said. That figure includes four people reported dead by their families.
Nixon told CNN's "State of the Union" earlier Sunday that Missouri state troopers made death notifications to families throughout the night, sitting with some families for hours as they grieved.
Some of those missing may be in the morgue, Nixon said. Damage to some of the bodies means DNA testing must be conducted in order to identify them.
The list of those who perished includes 1-year-old Hayze Howard, the youngest identified victim, and Nancy E. Douthitt, 94, the oldest, according to the Missouri Department of Public Safety.
Another child, 1-year-old Joshua Vanderhoofven, died along with his mother, Dee Vanderhoofven, according to her obituary in the Joplin Globe newspaper.
The list also includes Will Norton, an 18-year-old whose disappearance during the storm attracted national attention. The May 22 twister swept Norton out of the arms of his father as the two drove home from the son's high school graduation.
Asked why the number of fatalities was so high, Nixon cited the "total destruction" left by the twister. In one household, a young woman got into the home's bathtub, and her husband lay down on top of her to protect her, he said. The man was impaled by debris and died; the woman survived.
"Folks are beyond homeless here," the governor said. "Their homes don't exist ... the power and destruction here was unimaginable."
Obama's scheduled visit comes exactly one month after he visited Tuscaloosa, Alabama, where a tornado of similar force had ripped through the city and killed 41 people.
And on May 16, the president traveled to Memphis, Tennessee, to meet people displaced from their homes by a historic Mississippi River flood.
Meanwhile, a hospital that suffered a direct hit from the twister was reopening Sunday in a temporary facility and with a different name.
St. John's Regional Medical Center suffered heavy damage from the tornado, prompting the evacuation of its patients and staff. On Sunday, according to a statement from hospital spokesman Cora Scott, St. John's Mercy Hospital was beginning to see patients in its temporary facility across the parking lot from the damaged hospital building.
"The building is not St. John's," Dr. Bob Dodson, who is working to set up the temporary hospital, said in the statement. "St. John's is the people who worked in that building. And they're going to be the people in this building."
The temporary facility will have an emergency department, surgical suites, MRI and CT scan capabilities, a pharmacy and 60 inpatient beds. It is being build to withstand 100-mph winds, Scott said.
The temporary hospital will be in operation until a more permanent facility can be built, which will house the hospital while the campus is being reconstructed, according to the statement.
At 5:41 p.m. (6:41 p.m. ET) Sunday, exactly one week after the EF-5 tornado touched down in Joplin, the city observed a moment of silence for the victims, including those who have yet to be identified and others who may yet be found. Residents stood solemnly as American flags flapped in the wind.
As of Saturday, about 5,500 households in Jasper and Newton counties had applied for federal assistance, FEMA spokesman Bradley Carroll said. Some $6 million in aid had been approved for Jasper County residents and $200,000 for Newton County residents.
Norton's body was found Friday by divers in a pond close to where his vehicle had been. The tornado destroyed the Hummer H3 he and his father were in. A relative said the teen's father did all he could to keep his son from being swept away by the tornado.
"Mark (Norton's father) said that he reached over and he grabbed Will with both of his arms," said Tracey Presslor, Norton's aunt. "He held on to him until he possibly couldn't anymore, and so he's feeling really bad about that because as a dad you don't want to ever let go of your kids.
"You want to protect them forever," Presslor said as she cried. "But at least we know that he did absolutely everything he possibly could."
Meanwhile a "boil water" order was lifted for Joplin as of Saturday, according to Missouri American Water.
"Customers were asked to boil their water following (a) loss of pressure throughout the system from damages caused by the tornado," the company said in a statement. But tests confirmed the water is safe for consumption.
CNN's Casey Wian, Dugald McConnell and Michael Martinez contributed to this report.