A look back at the week in history
April 18, 1983 A suicide bomber kills 63 people at the U.S. embassy in Beirut, Lebanon.
April 19, 1993 The FBI launches an assault against the Branch Davidian religious cult in Waco, Texas, killing over 80 members.
April 20, 1999 Two students open fire and kill 13 people at Columbine High School in Littleton, Co.
April 22 , 1970 Earth Day is celebrated for the first time in the United States.
April 24, 1800 President John Adams establishes the Library of Congress.