Harris and Klebold enter the Columbine High cafeteria and open fire. They throw pipe bombs, which explode, filling the air with smoke and setting off the fire alarms.
Teacher Dave Sanders runs into the cafeteria to warn students, then heads upstairs. Harris and Klebold, following behind, shoot him in the hallway. Sanders crawls to a nearby room. Students try to save him, but he later dies.
The killers enter the library. Laughing and taunting students, they shoot many of their victims at point-blank range. Terrified students barricade themselves all over the school, from a kitchen freezer to the bushes outside. Several call relatives and police on cell phones.
About 12:30 p.m., SWAT teams enter the east side of the school and begin a room-by-room sweep of the upper level.
On the west side of the building, two other eight-man SWAT teams break a window of the teachers’ lounge and begin securing the lower level.
About 2:30 p.m., police begin freeing groups of hiding students. They are searched and treated before meeting waiting parents at Leawood Elementary School.
17-year-old Patrick Ireland, shot multiple times in the head, dangles from a second-floor window until SWAT-team members pull him to safety.
About 4:30 p.m., police find Harris and Klebold in the library. Apparent suicides, their bodies are close enough to touch. They are surrounded by the corpses of 10 of their victims. Police declare the site secure.
About 10:30 p.m., a bomb explodes. No one is hurt.
THE ARSENALHarris and Klebold used four high-powered guns and homemade explosives for their killing spree:
Double-barrel shotgun This older-model shotgun was sawed off ‘as much as you possibly could,’ said a federal agent, allowing for the buckshot to spray widely and cause more damage
TEC9 semiautomatic Popular with criminals, this handgun was one of the assault weapons banned by the 1994 Brady Bill
Pump shotgun Also sawed off, this shotgun fires shells with BB-size pellets
9-mm semiautomatic rifle Fires 10 rounds as fast as trigger can be pulled
Propane tank A 20-lb. gas tank was rigged with wiring, an egg timer and a fuse. Was set to blow up a sizable part of the school.
Pipe bombs More than 30 of these ‘very basic bombs’ were found. The cylinders were packed with gunpowder, nails and broken glass - to be more lethal
THE WARNING SIGNSWhile some described them as bright and well behaved, Harris and Klebold had started showing signs of trouble:
January 1998 Klebold and Harris, then 16, are caught breaking into a van to steal electronics. As first-time offenders, they are considered low risk and assigned to a county juvenile-diversion program.
July 4, 1998 The Trenchcoat Mafia runs into fellow Columbine student Peter Maher at 7-Eleven. After an exchange of words, Maher says Harris and Klebold wave a pistol at him from the window of Klebold’s BMW.
1998 Harris and Klebold make a video in which they pretend to shoot friends dressed as jocks.
1999 At least one teacher and two parents reportedly warn authorities that the two boys are violent.
Harris’s profile on an America Online Web site includes the quote “Kill ’em AALLL!!!”
April 20, 1999 Harris arrives at school wearing a T shirt that reads SERIAL KILLER. Later, after changing into all black, he tells a classmate that he likes him and advises him to go home immediately.
