April 20, 1999 – Two students walked into Columbine High School and began the deadliest school shooting in U.S. history.

Thirteen students were murdered, 21 were wounded. In addition, 99 explosive devices were placed around the school building and facilities, but only three detonated.

“The intent was to kill every student, teacher and first responder,” said Don Moseman, training director at the North Dakota Safety Council.