April 17 -In 1961, about 1,500 CIA-trained Cuban exiles launched the disastrous Bay of Pigs invasion of Cuba in a failed attempt to overthrow the government of Fidel Castro.
April 18 - In 1906, a devastating earthquake struck San Francisco, followed by raging fires. About 700 people died.
April 19 - In 1995, a truck bomb exploded outside the Alfred P. Murrah Federal Building in Oklahoma City, killing 168 people, and injuring 500. Timothy McVeigh was convicted of the bombing and sentenced to death.
April 20 - In 1999, two young men stormed into a suburban high school in Littleton, Colo., at lunch time with guns and explosives, killing 13 and wounding dozens more in what was at the time the nation's deadliest school massacre.
April 21 - In 1910, author Samuel Langhorne Clemens, better known as Mark Twain, died in Redding, Conn.
April 22 - In 1889, the Oklahoma Land Rush began at noon as thousands of homesteaders staked claims.