At 9:02 AM, Central, on April 19, 1995, a truck parked by Timothy McVeigh, containing 5,000lbs of ammonium nitrate exploded under the edge of the Murrah Federal Building in Oklahoma City, OK. Initially, due to the attack on the World Trade Center in NYC, by Al-Qaeda, a few years earlier, and the prevalence of islamist terrorism, Arab terrorists were the suspects.
Motivated by the fictional book, the Turner Diaries, McVeigh had solicited the assistance of fellow veterans of Desert Storm and 1st Infantry Division, Fortier and Nichols. He chose the date due to its historical significance and was outraged over the Waco incident 2 years prior as well as the Ruby Ridge incident. His anti-government rants had preceded his enlistment in the Army, and there is reason to believe he also harbored racist opinions, with potential encounters with organizations in Oklahoma and Arkansas, as well as Michigan and New York.
In order to finance his act of terrorism, McVeigh stole guns from a dealer in Arkansas, as well as the blasting caps from a mining operation in the Western US. He purchased the ammonium nitrate and mixed it with diesel and racing fuel, and with his co-conspirators tested the mix in small batches around his home in Kingman, AZ.
Of the 168 people killed, were dozens of children, a couple of Military Recruiters, and Secret Service Agents. His explosion was set to go off prior to one of his targets, the Bureau of Alcohol, Tobacco, and Firearms' normal workday. Neither the IRS, nor the FBI had offices in the Murrah Building.
McVeigh was arrested after a routine traffic stop North of OK City. He was driving a car with no license plate and speeding. The arresting officer noticed a gun bulging from his waistband for which he did not have a carry permit. McVeigh awaited arraignment for 3 days on the gun charges before it was realized that he was the subject of a national search, based on an artist's sketch.
McVeigh had personally gone to Waco during the standoff there, but had failed to realize that the agents that had initiated the attempted arrest of a child molestor, David Koresh, on automatic weapons charges had cautioned against the action, preferring to wait until the subject entered town. Nor did McVeigh take into account that following the botched attempt, the FBI had taken over the operation, under the direct orders of the US Attorney General, Janet Reno.
McVeigh was sentenced to death for the murder of the Federal Agents and use of explosives. Nichols was sentenced to life in prison. Fortier received a lesser sentence for turning state's evidence.
The act of terrorism fueled support for anti-gun laws and enhanced investigations into counter-government organizations, in other words, the exact opposite of what McVeigh claimed to want. The case has been used as a rallying cry for the "dangerous veterans" and "right-wing terrorists" crowd since that time, despite the rarity of either connection.
Annually, there are about a dozen animal rights and environmental action acts of terrorism inside the United States that go unreported. Since 9/11 there have been dozens of acts of terrorism perpetuated against Military Recruiting stations, including the NYC bombing, the Little Rock shooting, and others. Attacks on Embassies in NYC have also gone unreported but bear the hallmarks of the anti-war groups.