· The school custodian, after rewinding a recycled videotape, hits the record button on the VCR that records images of lunchtime activities in the school cafeteria. The tape immediately shows students near the windows beginning to notice something happening outside and some start toward the cafeteria windows to look.
· Jefferson County Sheriff's Deputy Neil Gardner, community resource officer at Columbine High School, has just finished his lunch while sitting in his patrol car at the students' "Smoker's Pit" when he receives a call from the school custodian on the school's radio. He's needed in the "back lot" of the school.
· A 911 call from a Columbine High School student reports a girl injured in the south lower parking lot of the high school. "I think she's paralyzed," the caller tells dispatch.
· Deputy Magor, on his way to the explosion in a field off Wadsworth, is advised of a female down in the south parking lot of Columbine High School.
· Deputy Gardner, pulling his car onto Pierce Street and heading south to the student parking lot, hears the same call, this time coming over the Sheriff's radio, "Female down in the south lot of Columbine High School." He activates his lights and siren.
· Several of the school's custodial staff and faculty, including teacher William "Dave" Sanders, are attempting to find out what is happening outside the school cafeteria.
· Realizing a danger, Sanders and school custodians Jon Curtis and Jay Gallatine enter the cafeteria and direct students to get down. Students begin to hide under the cafeteria tables.
· Deputy Paul Smoker, a motorcycle patrolman for the Jefferson County Sheriff's Office, is writing a speeding ticket on West Bowles Avenue, just west of Pierce Street, when he hears dispatch report that a female is down in the south lower lot of Columbine High School. Smoker's traffic stop is just north of the school so he radios dispatch that he is responding to the school.
· Teacher Patricia (Patti) Nielson is working as a hall monitor when she hears a commotion outside the west entrance of the school. She looks outside, seeing two male students with what she thinks are toy guns, and assumes that a school video production is being taped. She is on her way outside to tell the boys to "knock it off" when one of the gunmen fires into the west entrance, causing glass and metal fragments to spray into the hallway. Nielson suffers abrasions to her shoulder, forearm and knee from the fragments.
· Beside Nielson is student Brian Anderson. Brian had been told by a teacher to get out of the school because of the explosions and commotion. Not realizing where the danger is, he exits through the first set of west doors, and is caught between the interior and exterior doors when Harris fires at the doors in front of him, shattering the glass. Brian suffers wounds to his chest from the flying glass fragments.
· Despite their injuries, Patti Nielson and Brian are able to flee into the school library while Harris and Klebold are distracted by the arrival of Deputy Gardner. Gardner has just pulled up in the lower south parking lot of the school with the lights on his patrol car flashing and the siren sounding.
· As Gardner steps out of his patrol car, Eric Harris turns his attention from shooting into the west doors of the high school to the student parking lot and to the deputy. Gardner, particularly visible in the bright yellow shirt of the community resource officer's uniform, is the target of Harris' bullets. Harris fires about 10 shots at the deputy with his rifle before his weapon jams.
· Gardner fires four shots at Harris.
· Harris spins hard to his right and Gardner momentarily thinks he has hit him. Seconds later, Harris begins shooting again at the deputy. Although Gardner's patrol car is not hit by bullets, two vehicles that he is parked behind are hit by Harris' gunfire. Investigators later found two bullet holes in each of the cars.
· Harris then turns and enters the school through the west doors.
· Students in the cafeteria realize the activity occurring outside is more serious than a senior prank. A mass exodus of students is seen on the school's surveillance videotape as students escape up the stairs from the cafeteria to the second level. Several students recalled Sanders directing them to safety by telling them to go down the hallway to the east side exits of the school.
· Jefferson County Sheriff's Office dispatch advises that there are possible shots fired at Columbine High School. "Attention, south units. Possible shots fired at Columbine High School, 6201 S. Pierce, possibly in the south lower lot towards the east end. One female is down."
· Teacher Patti Nielson, hiding under the front counter in the school library, calls 911 to report shots being fired outside the library.
· Littleton Fire Department dispatches a fire engine to the explosion and grass fire on Wadsworth.
· After exchanging gunfire with Harris, Gardner calls on his police radio for additional units. "Shots in the building. I need someone in the south lot with me."
· Dispatch reports several shots fired at Columbine High School.
· Teacher's 911 call from inside the library reports smoke coming in through the doorway. She yells at students to get on the floor and under the tables.
· Jefferson County Deputies Scott Taborsky and Paul Smoker arrive on the west side of the school and begin the rescue of two wounded students lying on the ground near the ball fields.
· Smoker sees Gardner down the hill to his right, holding a service pistol. Gardner yells to Smoker as a gunman, carrying a semi-automatic rifle, appears on the inside of the double doors.
· Harris, leaning out of a broken window on the set of double doors into the school, begins shooting a rifle. Smoker fires three rounds at him and the gunman disappears from the window. Smoker continues to hear gunfire from inside the building as more students flee from the school.
· Student witnesses who entered the north main hallway from adjoining classrooms see Klebold and Harris standing just inside the school's northwest entry doors. Both suspects, they later recalled, are armed with guns. Witnesses see Klebold fire a semi-automatic weapon east towards the students in the main hallway and south down the library hallway. They also hear bullets hitting lockers and other objects in the hallway as students run for cover.
· A student in the gym hallway observes Klebold and Harris walking east down the north hallway. Both are firing weapons … and both are laughing.
· Student Stephanie Munson and another student walk out of a classroom into the school's north main hallway. As they enter the hallway, they see a teacher and several students running behind them. The teacher yells for the students to "Run! Get out of the building!" They both run through the main hallway leading to the school's main entrance on the east side. Stephanie is shot in the ankle but both are able to escape the building and continue across the street to safety at Leawood Park.
· A student in the counseling hallway sees students in the north hallway running east through the lobby. Klebold is running behind them, but comes to an abrupt halt near a bank of phones at the entrance to the main lobby area.
· Yet another student, on the telephone with her mother, glances up in time to see the sleeve of a black trench coat shooting a TEC-9 towards the main entrance of the school. She drops the phone and hides in a nearby restroom until she can no longer hear any activity in the hallway. The gunman, she assumes, has turned around and gone back the other way. She goes back to the phone and whispers to her mother to come pick her up and then escapes through the east doors to the outside. Her mother's cell phone bill shows this call is made between 11:23 and 11:26 and lasts 3.8 minutes. The student estimates that she talks to her mother about two minutes before she sees the gunman.
· Klebold is last seen running back down the north hall to the west in the direction of the library hallway.
· Teacher Dave Sanders, still on the second level, turns into the library hallway toward the west entrance and the sounds of gunfire. As Sanders passes the entrance to the library, he apparently sees a gunman coming toward him from the north hallway. Sanders turns around and heads back the way he had just come. Just before turning the corner to go east, he is shot. Sanders is able to crawl to the corner of the Science hallway where teacher Richard Long helps him down the hallway into classroom SCI-3. A group of students, including two Eagle Scouts, Aaron Hancey and Kevin Starkey, gather around him, attending to his injuries and administering first aid.
· Deputy Gardner, who is in the south parking lot and has exchanged gunfire with Eric Harris, radios dispatch with a "Code 33." Code 33 means "officer needs emergency assistance."
· Deputy Magor sets up a road block on Pierce Street at the southeast corner of the student parking lot. He immediately is approached by a teacher as well as students reporting a person in the school with a gun.
· Dispatch announces that possible hand-grenades have been detonated at the school.
· Harris and Klebold walk up and down the library hallway, randomly shooting but not injuring anyone. Investigators later scrutinized Nielson's 911 call made from the school's library. From the tape, the investigation shows that Harris and Klebold spend almost three minutes in the library hallway randomly shooting their weapons and lighting and throwing pipe bombs. They throw two pipe bombs in the hallway and more over the stairway railing to the lower level.
· A pipe bomb is thrown into the stairwell from the library hallway and lands in the cafeteria below. A large flash is observed on the cafeteria videotape. A second pipe bomb also is thrown into the cafeteria from the upper level.
· Teacher Patti Nielson, hiding under the front counter just inside the library entrance, continues her phone contact with the Jefferson County dispatcher. Nielson reacts to the sounds of gunshots and explosions coming from the hallway outside the library. Interspersed with short conversations with the dispatcher, she screams at the students in the library to get under the tables and to stay hidden. She then reports that a gunman is just outside the library entrance.