On April 19, 1995, a truck bomb was detonated outside the Alfred P. Murrah Federal Building in Oklahoma City, Oklahoma, killing 168 people and injuring over 600. The bombing became the deadliest act of domestic terrorism in the United States and led to sweeping reforms in United States federal building security. The attack's perpetrator, Timothy McVeigh, was an anti-government extremist who used the Waco Siege and Ruby Ridge incidents as justification for his retaliation against the federal government. While McVeigh wanted to specifically target the federal agencies involved in the Waco siege, such as the ATF and DEA, the bombing killed many innocent civilians, including 19 children. McVeigh was executed in 2001 and his accomplice Terry Nichols was sentenced to life in prison.