20 years ago, on April 19th 1994, anti-government terrorists Timothy McVeigh and Terry Nichols set off a large bomb outside the Murrah Federal Building in Oklahoma City, killing 168 people and injuring at least 680.
The attack was made in retaliation for the Ruby Ridge incident and Waco, Texas siege, which occurred two years prior, to the day. McVeigh and Nichols were tried and convicted in 1997, the former being sentenced to death by lethal injection and the latter receiving a life sentence.