The deadly shooting spree, described by police as a probable "suicide mission", took place at Columbine High School in the quiet residential suburb of Littleton, south-west of Denver, and revived memories of last year's string of fatal school shootings.
The horrific drama, chronicled minute by minute on local and national television, began at 11.30am local time, when explosions and shots were heard from inside the school.
According to distressed pupils who emerged from the building over the next six hours, two heavily armed white men, wearing long black trench coats and wearing masks, burst into the school canteen and opened fire indiscriminately. Several said that the gunmen had been carrying either grenades or pipe bombs under their coats. Some pupils said the gunmen targeted athletes, and ethnic minorities (blacks and Hispanics). One girl said a black pupil near her in the canteen had been shot in the face.
The two had been spotted earlier apparently staking out the building in the hour before the shooting began. One pupil told local television: "I was hiding behind the bushes. I saw the men with the weapons inside the school. They were stalking around, I assume looking for people to kill. I'm praying to the Lord that they don't come out the back door."
According to one eye witness, the men were armed with two pistols and an Uzi-type weapon apiece. After shooting at random in the canteen, they ran to the library, still shooting, pursuing some of their victims onto the school soccer field.
One pupil said a third man in a white T-shirt threw bombs into the library and then chased pupils out into the field, "kind of shooting randomly". His whereabouts last night were unclear.
Outside the school vanloads of heavily armed police and fleets of ambulances arrived. Dozens of worried parents rushed to the scene.
Pupils spoke of cowering under desks from where they saw their friends fall, shot and bleeding, to the ground. Others had fled into neighbouring parkland or on to the roof.
As helicopters wheeled overhead, local television covered the scene live, showing preparations for the Swat (heavily armed and armoured rapid reaction team) teams to force their way into the school. Two hours after the arrival of police and emergency services, three young men were apprehended in the school grounds, after apparently giving themselves up to police. They were later described as accomplices of the gunmen. The two gunmen, however, remained inside the school, reportedly holding more than a dozen pupils hostage.
As the hours passed, groups of children ran from the school buildings with their hands over the heads, as instructed by police. Local television reporters said they had seen children apparently with gunshot wounds and covered with blood.
Four hours into the incident, the Swat teams finally entered the building; they were still sweeping the premises two hours later, searching for any pupils and staff who might remain inside. The county sheriff spoke of "numerous dead" and extensive damage to the building.
Several pupils said they recognised the gunmen as pupils or former pupils and spoke of a clique that wore black trench coats to school every day. "They wore black, long trench coats and were associated with death and violence," said Josh Nielson, who added they were known as the Trenchcoat Gang or Trenchcoat Mob and numbered about 20. He also said they were shunned by other pupils.
Another pupil said the gang had made predictions and threats alluding to the coming millennium.
A neighbour of one of the dead gunmen said the youth had threatened his son with pipe bombs on several occasions in the past and that he was known to have Nazi sympathies. The youth had warned that something could happen on the anniversary of Hitler's birthday (which fell yesterday).
In a special television broadcast last night, President Bill Clinton - a long-time campaigner for stricter gun controls - said that perhaps now America would "wake up to the dimensions of this challenge if it could happen in a place like Littleton". Announcing that he was sending a crisis response team to Colorado, Mr Clinton called for more to be done to help children express their anger with words not weapons.
Yesterday's attack resumed the deadly spate of school shootings that has horrified the United States over the past 18 months. Between October 1997 and last May, there were at least six shootings on school premises which killed pupils and staff. Three pupils were killed by a 14-year- old pupil in West Paducah, Kentucky, in December 1997, and five by an 11- and a 13-year-old in Jonesboro, Arkansas, the following March.Reuse content