(CNN) -- Here's a look at what you need to know about the Birmingham, Alabama church bombing that killed four African-American girls during church services in 1963.
September 15, 2013 marks the 50th anniversary of the bombing.
Facts: September 15, 1963 - A bomb blast at the Sixteenth Street Baptist Church in Birmingham, Alabama, kills four African-American girls during church services. At least 14 others are injured in the explosion.
Three former Ku Klux Klan members are convicted of murder for the bombing.
Victims: Addie Mae Collins, 14 Denise McNair, 11 Carole Robertson, 14 Cynthia Wesley, 14
Timeline: September 15, 1963 - Four girls are killed and 14 injured in a bomb blast at the Sixteenth Street Baptist Church in Birmingham, Alabama. Riots break out, and two African-American boys, Virgil Ware, 13, and Johnny Robinson, 16, are also killed. In all, at least 20 people are injured from the initial bombing and the ensuing riots. Alabama Governor George Wallace sends 500 National Guardsmen and 300 state troopers to the city. The next day, they are joined by 500 police officers and 150 sheriffs' deputies.
September 16, 1963 - President John F. Kennedy responds by saying, "If these cruel and tragic events can only awaken that city and state - if they can only awaken this entire nation to a realization of the folly of racial injustice and hatred and violence, then it is not too late for all concerned to unite in steps toward peaceful progress before more lives are lost."
September 16, 1963 - Dr. Martin Luther King, Jr. holds a press conference in Birmingham, saying that the U.S. Army "ought to come to Birmingham and take over this city and run it."
1965 - Suspects emerge: Bobby Frank Cherry, Thomas Blanton, Robert Chambliss, and Herman Frank Cash, all Ku Klux Clan members. Witnesses are reluctant to talk and physical evidence is lacking so charges are not filed.
1976 - Alabama Attorney General Bill Baxley reopens the case.
September 26, 1977 - Robert Chambliss, 73, a retired auto mechanic and former Ku Klux Klan member, is indicted by a Jefferson County grand jury on four counts of first-degree murder.
November 15, 1977 - On the second day of the trial, Chambliss's niece, Elizabeth Cobb, testifies that before the bombing, Chambliss confided to her that he had "enough stuff put away to flatten half of Birmingham."
November 18, 1977 - Robert Chambliss is convicted of first-degree murder in connection with the bombing and sentenced to life imprisonment.
1985 - Chambliss dies in prison.
1994 - Herman Frank Cash dies without being charged in the bombing.
July 1997 - The case is reopened by the FBI, citing new evidence.
May 16, 2000 - A grand jury in Alabama indicts former Klansmen Bobby Frank Cherry and Thomas Blanton with eight counts each of first-degree murder - four counts of intentional murder and four of murder with universal malice.
May 1, 2001 - Thomas Blanton is found guilty of first-degree murder and is sentenced to four life terms.
November 8, 2004 - Cherry dies in prison.
February 20, 2006 - The Sixteenth Street Baptist Church is declared a national historic landmark.
September 12, 2013 - 50 years after the bombing, all four girls who died are awarded Congressional Gold Medals.
September 14, 2013 - A bronze and steel statue of the four girls is unveiled. It is located at Kelly Ingram Park, on the corner of Sixteenth Street North and Sixth Avenue North.