The attack took place at 9:02 A.M. on April 19, 1995, when a truck bomb exploded outside the Alfred P. Murrah Federal Building in Oklahoma City, Oklahoma. Of the 168 people who were killed, 19 were children. Another 500 people were injured. The blast, which investigators later learned had been caused by a bomb made of more than two tons of ammonium nitrate and fuel oil, sheered off the front half of the nine-story building and left a crater 8 feet deep and 30 feet wide. Nearby buildings were damaged or destroyed, including a YMCA day care center where many children were seriously injured. The force of the explosion shattered windows blocks away. Survivors of the blast and others in the vicinity began rescue efforts right away. Eventually more than 3,600 people from around the country participated in rescue operations, including police, firefighters, and members of the Federal Emergency Management Agency (FEMA).

Police and Federal Bureau of Investigation (FBI) agents arrested members of an American right-wing militant group who were suspected of wanting to avenge the April 19, 1993, FBI/ATF raid on the Branch Davidian religious compound in Waco, Texas. Former army buddies Timothy J. McVeigh, then 27, and Terry L. Nichols, then 40, were indicted on August 10, 1995, on 11 charges each. The two were tried separately and convicted in federal court. McVeigh was found guilty of murder and conspiracy in June 1997, and a federal jury sentenced him to death. Nichols was later found guilty of conspiracy and involuntary manslaughter, but in January 1998 the jury deadlocked on the sentence, which was then to be decided by the judge. In early June it was decided that Nichols would serve life in prison.

Officials believe the Murrah Federal Building was targeted in the antigovernment attack because it housed 15 federal agencies, including offices of the Social Security Administration (SSA), Housing and Urban Development (HUD), the Drug Enforcement Administration (DEA), and the Bureau of Alcohol, Tobacco, and Firearms (ATF), as well as several defense department offices and a government-run day care center.