A 911 dispatcher reached by frantic students trapped inside Columbine High School is heard telling students to "encourage" wounded teacher Dave Sanders as he lay bleeding to death from gunshot wounds.
"Don't let him close his eyes," the dispatcher said.
"We're having a hard time keeping him alert," an adult told the dispatcher, who responded by saying help was on the way and later added: "Make sure he stays warm."
SWAT teams didn't reach Sanders until nearly four hours after the shooting started April 20, 1999. Twelve students were also slain by Eric Harris and Dylan Klebold before they killed themselves.
The exchange involving Sanders is on 22 edited audio tapes, each 90 minutes long, released to the public Wednesday. The tapes of 911 and dispatch audio originally were sought by parents of two slain students and were released under a court order.
Missing from the tapes is a complete version of the 26-minute call placed by teacher Patti Nielson from the library, where most of the victims were killed.
Her call included the gunmen taunting students, screams and gunshots which a judge likened to gruesome crime scene photographs that did not need to be released.
"I can't believe he's not out of bullets; he just keeps shooting and shooting and shooting," Nielson said in a portion of her 911 call released Wednesday.
Families of at least 15 slain or wounded students have filed lawsuits accusing the Jefferson County Sheriff's Office of negligence in its handling of the massacre. Some families have criticized the sheriff's official report of the massacre and have called for the release of raw investigative material.
Radio traffic from five police channels did not immediately address whether deputies were denied permission to fire at the gunmen. Angela Sanders, the slain teacher's daughter, contends in a lawsuit that a sharpshooter on the roof of a nearby house had a "clear view" of Klebold through a library window, but was told not to fire.
A sheriff's dispatcher on the tapes asks deputies on the scene if anybody had "long arms," or rifles. One deputy answered that he did, but the conversation turned to SWAT teams and a supervisor on the way.
One deputy reported seeing a gunman appear briefly in the library window at about 11:32 a.m., but he did not ask for permission to fire.
On another portion of the tape, an out-of-breath deputy reported exchanging gunfire with one of the two student killers.
"It was a big gun," he said.
Most of the 911 calls came from parents asking about their children's whereabouts and from students trapped inside the school.
Some of the information released Wednesday had already been released May 15 as part of the official report.
Jefferson County District Judge R. Brooke Jackson has also ordered the sheriff's office to release a Littleton Fire Department training tape, raw television footage shot from a helicopter, surveillance tapes and the ballistics report.
CBS Worldwide Inc. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. The Associated Press contributed to this report