The Oklahoma City bombing occurred when a truck packed with explosives was detonated on April 19, 1995, outside the Alfred P. Murrah Federal Building in Oklahoma City, Oklahoma, killing 168 people and leaving hundreds more injured. The blast was set off by anti-government militant Timothy McVeigh, who in 2001 was executed for his crimes. His co-conspirator Terry Nichols was sentenced to life in prison. Until September 11, 2001’s World Trade Center attacks, the Oklahoma City bombing was the worst terrorist attack to take place on U.S. soil.

Alfred P. Murrah Federal Building

Shortly after 9:00 a.m. on April 19, 1995, a Ryder rental truck exploded with terrifying force in front of the nine-story Alfred P. Murrah Federal Building in downtown Oklahoma City.

The powerful explosion blew off the building’s entire north wall. Emergency crews raced to Oklahoma from across the country, and when the rescue effort finally ended two weeks later, the death toll stood at 168 people.

The list of the deceased included 19 young children who were in the building’s day care center at the time of the blast. More than 650 other people were injured in the bombing, which damaged or destroyed over 300 buildings in the immediate area.

WATCH: Oklahoma City Bombing on HISTORY Vault

Did you know? The Alfred P. Murrah Federal Building opened in 1977 and was named for an Oklahoma native who became one of the youngest federal judges in U.S. history when he was appointed by President Franklin Roosevelt in 1936. Murrah died in 1975 at age 71.

Timothy McVeigh

A massive hunt for the bombing suspects ensued, and on April 21 an eyewitness description led authorities to charge Timothy McVeigh, a former U.S. Army soldier, in the case.

As it turned out, McVeigh was already in jail, having been stopped a little more than an hour after the bombing for a traffic violation and then arrested for unlawfully carrying a handgun. Shortly before he was scheduled to be released from jail, he was identified as a prime suspect in the bombing and charged.

That same day, Terry Nichols, an associate of McVeigh’s, surrendered in Herington, Kansas. Both men were found to be members of a radical right-wing survivalist group based in Michigan.

On August 8, Michael Fortier, who knew of McVeigh’s plan to bomb the federal building, agreed to testify against McVeigh and Nichols in exchange for a reduced sentence. Two days later, McVeigh and Nichols were indicted on charges of murder and unlawful use of explosives.

Domestic Terrorists Behind the Oklahoma City Bombing

While still in his teens, McVeigh, who was raised in western New York, acquired a penchant for guns and began honing survivalist skills he believed would be necessary in the event of a Cold War showdown with the Soviet Union.

He graduated from high school in 1986 and in 1988 enlisted in the Army, where he proved to be a disciplined and meticulous soldier. While in the military, McVeigh befriended fellow soldier Nichols, who was more than a dozen years his senior and shared his survivalist interests.

In early 1991, McVeigh served in the Persian Gulf War. He was decorated with several medals for his military service; however, after failing to qualify for the Special Forces program, McVeigh accepted the Army’s offer of an early discharge and left in the fall of 1991.

At the time, the American military was downsizing after the collapse of the Soviet Union. Another result of the end of the Cold War was that McVeigh shifted his ideology from a hatred of foreign communist governments to a suspicion of the U.S. federal government, especially as its new leader Bill Clinton, elected in 1992, had successfully campaigned for the presidency on a platform of gun control.

McVeigh, Nichols and their associates were deeply radicalized by such events as the August 1992 shoot-out at Ruby Ridge, Idaho, between federal agents and survivalist Randy Weaver at his rural cabin, and the Waco siege of April, 1993, in which 75 members of a Branch Davidian religious sect died near Waco, Texas.

McVeigh planned an attack on the Murrah Building, which housed regional offices of such federal agencies as the Drug Enforcement Agency, the Secret Service and the Bureau of Alcohol, Tobacco and Firearms and Explosives, the agency that had launched the initial raid on the Branch Davidian compound.

On April 19, 1995, the two-year anniversary of the disastrous end to the Waco siege, McVeigh parked a Ryder rental truck loaded with a diesel-fuel-fertilizer bomb outside the Murrah Building and fled. Minutes later, the massive bomb exploded.

McVeigh and Nichols Sentenced

On June 2, 1997, McVeigh was convicted on all 11 counts against him, and on August 14 the death penalty was formally imposed.

The following year, Fortier, who had met McVeigh in the Army, was sentenced to 12 years in prison for failing to warn authorities about the Oklahoma City bombing plan. Fortier was released from prison in 2007 and entered the witness protection program.

In December 1997, Nichols was found guilty on one count of conspiracy and eight counts of involuntary manslaughter, for killing federal law enforcement personnel, and was sentenced to life in prison. In 2004, he was tried on state charges in Oklahoma and convicted of 161 counts of first-degree murder, including fetal homicide. He received 161 consecutive life terms in prison.

Oklahoma City National Memorial Museum

In December 2000, McVeigh asked a federal judge to stop all appeals of his convictions and to set a date for his execution.

The request was granted, and on June 11, 2001, McVeigh, at age 33, died by lethal injection at the U.S. penitentiary in Terre Haute, Indiana. He was the first federal prisoner to be put to death since 1963.

In May 1995, the Murrah Building was demolished for safety reasons, and the Oklahoma City National Memorial Museum later opened at the site.