Investigators continue their work around the front entrance of Columbine High School

A teacher in the library talks with 911 as shots are fired in the background. AIFF or WAV (349 K/30 sec. audio) RELATED AUDIO Police dispatcher talks to officers rushing to scene Real 28K 80K Windows Media 28K 80K Teacher tells students to stay down as gunshots ring out in the background Real 28K 80K Windows Media 28K 80K A student outside the school describes what she saw Real 28K 80K Windows Media 28K 80K RELATED VIDEO: Media from around the world converge on Colorado, along with CNN's Anne McDermott (April 23) Real 28K 80K Windows Media 28K 80K Correspondent Deborah Feyerick reports on the use of cell phones by students and how school officials feel about them Real 28K 80K Windows Media 28K 80K The shooting has brought the debate over gun control into the forefront. CNN's Judy Woodruff explains. (April 22) Real 28K 80K Windows Media 28K 80K Security is not the same at all schools. CNN's Eileen O'Connor reports. (April 22) Real 28K 80K Windows Media 28K 80K To view the latest video streams on the Littleton school shooting, use the arrow buttons below to scroll through the video gallery.        Windows Media Real        28 K 80 K INTERACTIVE: See more scenes from the shooting Audio and Images Interactive Map: Recent school shootings in the U.S. Special: Are schools safe?  ALSO: Shooting sparks renewed political debate over guns Fatalities at Columbine High List of injured from Colorado school attack The aftermath Detailed map of Columbine High School Harris hinted at violence to come  MESSAGE BOARD: Colorado school shooting

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Are schools safe?

Weapons found during the investigation: One 9 mm semi-automatic pistol One 9 mm semi-automatic rifle Two sawed-off 12-gauge shotguns More than 30 homemade explosives, some with shrapnel

April 23, 1999
Web posted at: 5:07 p.m. EDT (2107 GMT)

In this story: Guns changed hands Video could be 'crucial' Federal help Gore to attend Sunday memorial RELATED STORIES, SITES

LITTLETON, Colorado (CNN) -- Investigators Friday released chilling tapes of 911 calls made from Columbine High School during Tuesday's gun and bomb massacre, including a plea for help from a terrified teacher trapped in the library with her students.

"There's smoke going up in the parking lot right now," said the female student who made the first 911 call. "People are running out of the school like mad."

The female teacher called from under a table in the school library, the scene of the worst carnage.

"Oh God, oh God ... he's upstairs, he's right outside of here," she screamed. "There's someone coming into this room. I'm on the floor. My God, smoke is coming into the room."

The dispatcher tells her to stay on the floor.

"On the floor, everybody, stay on the floor!"

The sounds of at least six gunshots followed.

Steve Davis, spokesman for the Jefferson County Sheriff's Department, then played police radio traffic of officers responding to the call, complete with sirens wailing.

Investigators trying to determine if other people were involved in the massacre or in efforts to booby-trap the school have interviewed hundreds of people and may be helped by video from a security camera, authorities said Friday.

Authorities have found no physical evidence against anyone but gunmen Eric Harris, 18, and Dylan Klebold, 17, but say the elaborate nature of Tuesday's attack in the Denver suburb of Littleton suggested the work of several people.

On Friday, after a large meeting to compare evidence and statements from an estimated 500 witnesses, the investigators left with renewed interest in reports that more than two people participated in the attack, officials told CNN.

Asked about reports of more than two assailants, Jefferson County Sheriff's Department spokesman Steve Davis said, "We've heard that from some students, so our attempt is to either prove or disprove that."

The Colorado Attorney General said his office was involved in the search of a home elsewhere in the Denver area in connection with Tuesday's attack. There was no information on whether anything was seized from the home in Arvada, Colorado.

As some investigators conducted interviews with students and others who might have useful information, police also returned to Columbine to continue scouring for hidden explosives.

On Thursday, the discovery of a bomb made from a 20-pound propane tank heightened suspicions that Harris and Klebold intended to destroy the school, and could have had help in assembling their arsenal.

The device, with nails and other shrapnel attached, was removed without incident.

Aside from the large bomb, searches have turned up more than 30 homemade explosives, including pipe bombs and crude hand grenades. More may remain hidden, authorities said.

Two sawed-off shotguns, one semi-automatic rifle and one semi-automatic handgun also have been found.

The rifle and handgun have been traced to their original owner but Jefferson County Sheriff's Department spokesman Steve Davis said Friday there was no link between the original owner and the high school gunmen.

"We don't know how many times those guns changed hands before getting to our suspects," he said.

Investigators were still trying to trace the shotguns.

Colorado Gov. Bill Owens, who toured the school on Friday, left saying investigators are all but certain the two gunmen had help.

"There are backpacks with bombs in there everywhere," Owens said. "The officers in there are convinced there had to be more people involved. There's just too much stuff in there."

Time-lapse security cameras mounted throughout the school do not run continuously, though they record about a week at a time, said Lt. John Kiekbusch of the Jefferson County Sheriff's Department.

A surveillance video from Saturday night, when there was an after-prom party at the school, "has the potential to be extremely important," he said.

"We don't know how much (of) that time period might turn out to be on those videos, but it certainly has the potential to be very, very crucial evidence in terms of movement of people throughout that school," Kiekbusch said.

"Ideally," he said, "they would show the movement and also the actual placement perhaps of some of the explosive devices, prior to the incident. If that's the case we have got just very important evidence."

President Clinton announced $1.5 million in federal aid Friday to help victims pay for funerals, medical expenses, lost wages and counseling.

The money is an initial payment to help the students, teachers and parents in Littleton on "their long journey toward recovery. And we will do more," the president said.

"The images from Colorado have become painfully familiar: the terrified children, the racing ambulances, the grieving families," Clinton said outside the White House.

"Still, it is important to remember that the vast majority of schools are safe," he added.

The president also reminded school officials across the country of federal programs to help prevent violent eruptions of rage. Among them:

• Early warning guides sent to 200,000 schools in August will be reprinted and distributed next week to 150,000 additional schools.
• Schools have until the end of this month to apply for a portion of the $17 million available for school crime prevention programs.
• Local communities have until June 1 to apply for some $180 million in Safe Schools/Healthy Students grants, a federal anti-violence and anti-drug-abuse initiative.
• A total of $70 million is available from the Justice Department for stationing some 600 police officers for school security in 336 communities around the country.

Next to Columbine High School, in Clement Park, a Sunday afternoon memorial service is planned for the one teacher and 12 students gunned down before their two murderous classmates turned their guns on themselves.

Vice President Al Gore and his wife, Tipper, planned to attend. Clinton was staying in Washington for the three-day NATO summit which began on Friday.

Thomas says he doesn't know why the shootings happened at Columbine High School, but he urges the media to 'help solve the problem of violence'

With Columbine closed indefinitely, Principal Frank DeAngelis said students will resume classes at a building off campus next week. He told CNN that, despite the tragedy, students want to return to the building someday.

"They said, 'Mr. DeAngelis, don't let them take our building from us, no one is going to chase us out, we have too much tradition there, too much pride, it's a great high school, we want back in,'" the principal said.

The principal said there was little that could have been done to prevent the attacks. "One (law enforcement agent) made the comment that the National Guard could ... not (have) prevented this," he said.

Jefferson County District Attorney Dave Thomas, admitting he was as confused as the rest of the world on how such violence can occur -- and how to prevent it -- made an impassioned appeal to the news media "to join with this community and with the people in this country ... to help solve the problem of human violence against other human beings."

"I'm an ordinary man," he said. " I don't have the answers."