The worst school shooting in US history has left America stunned as the country tries to get to grips with the massacre of up to 25 high school students in Colorado by two or three youths on what is called a "suicide mission".
While the bodies were still inside the building last night, a local sheriff said there were "possibly as many as 25 fatalities."
Two of the suspects, who were students in the school, were found dead from apparently self-inflicted wounds in the library. A third youth was arrested but it is not clear if he was involved in the shooting and bombing which turned the inside of Columbine High School in a Denver suburb into a slaughter-house.
Hundreds of students were hurried from the building by police SWAT squads which rushed there as the first reports of the shootings emerged. Students ran to safety from the building escorted by police who ordered them to hold their hands behind their heads until they were sure that the suspects were not among them.
There were scenes of panic as other teenage students escaped by their own efforts and ran for refuge across the school grounds.
At least 20 students are being treated for wounds, some in critical condition.
A shocked President Clinton went on nationwide TV to express his sadness at the tragedy in the affluent Littleton suburb of Denver.
This is the latest in a series of school shootings over the past two years which have resulted in 14 deaths and 44 injured. President Clinton said he would not like to call the series of school shootings "an epidemic."
He said he wanted to wait to get all the facts before drawing conclusions. But "we must do more to reach out to children and teach them to express their anger with words not weapons." It was also vital to look out for "warning signs" of such school violence. He said that a "crisis response team" of counsellors had been sent to the scene.
The killings began at 11.30 a.m. local time when two heavily armed youths began firing and throwing explosive devices. Students said that they were dressed in black and had masks. Some said that a third youth in a white shirt was also involved.
One girl told reporters that the attackers were picking out coloured students and even athletes.
Another student said that the two gunmen were students who were members of the so-called Trench Coat Mafia, a group of about eight students who always wore black coats to school. Another student described them as "outcasts" who were disliked.
Sheriff John Stone of Jefferson County told reporters that "there are possibly as many as 25 fatalities." He said that the scene inside the library where the bodies of the two suspects were found was "gruesome."
Students and teachers fled from the gunmen and sought safety in toilets and classrooms. Some students contacted their parents on mobile phones to tell them what was happening.
Hundreds of anguished parents and relatives converged on the school as the local police called up reinforcements including an armoured personnel carrier from the National Guard.
The heavily armed SWAT teams were the only persons allowed enter the school. The reports of 25 dead came from these teams as they conducted a sweep through the corridors and classrooms where many terrified students were hiding from the gunmen.
One girl described in tears how "everyone around me got shot and I begged him for 10 minutes not to shoot me and he just put the gun in my face. He started laughing and saying that it was all because people were mean to him last year."
A girl called Janine said that the gunmen "walked down the stairs and they started shooting people. We didn't think it was real and then we saw the blood."
Some of the students who escaped were able to tell the police the names of the gunmen although first descriptions said that they wore masks.
A police spokesman said that possible bombs were found on the dead suspects and a device found at the home of one of them may have been a homemade bomb.