Birmingham, Alabama, 16th Street Baptist Church bombing on September 15, 1963

The 16th Street Baptist Church bombing was an act of white supremacist terrorism which occurred at the African-American 16th Street Baptist Church in Birmingham, Alabama on Sunday, September 15, 1963, when four members of the Ku Klux Klan planted a minimum of 15 sticks of dynamite attached to a timing device beneath the front steps of the church.

Described by Dr. Martin Luther King, Jr. as "one of the most vicious and tragic crimes ever perpetrated against humanity," the explosion at the church killed four girls and injured 22 others.

Although the FBI had concluded in 1965 that the 16th Street Baptist Church bombing had been committed by four known Ku Klux Klansmen and segregationists: Thomas Edwin Blanton, Jr.; Herman Frank Cash; Robert Edward Chambliss; and Bobby Frank Cherry, no prosecutions ensued until 1977, when Robert Chambliss was tried and convicted of the first degree murder of one of the victims, 11-year-old Carol Denise McNair. Thomas Blanton and Bobby Cherry were each convicted of four counts of murder and sentenced to life imprisonment in 2001 and 2002 respectively, whereas Herman Cash, who died in 1994, was never charged with his alleged involvement in the bombing.

The 16th Street Baptist Church bombing marked a turning point in the United States 1960s Civil Rights Movement and contributed to support for passage of the Civil Rights Act of 1964.
https://en.wikipedia.org/wiki/16th_Street_Baptist_Church_bombing