Photo: Columbine bomb hoax Dec. 2018 | AP

A member of the Jefferson County, Colo., Sheriffs Department stands guard outside the main driveway to Columbine High School Thursday, Dec. 13, 2018, in Littleton, Colo. Students were kept inside the building as a large police response was summoned because a caller claimed to have placed explosive devices in the school and was hiding outside with a weapon. The call was determined to be false.