Wednesday, April 21, 1999 Published at 17:43 GMT 18:43 UK
Massacre school search continues
An agent checks cars for explosives outside the school
Police are continuing their search of a Colorado school where two gunmen killed 13 people before turning their guns on themselves.
The pair, who reportedly belonged to school clique called the "Trenchcoat Mafia", wore long black coats and masks and laughed repeatedly as they shot dead 12 students and one teacher.
It is the United States' worst school massacre. There has been a spate of similar killings over recent years.
US President Bill Clinton used a speech to White House volunteers on Wednesday to express national shock at the tragedy.
Police moved slowly through the school after one bomb with a timer exploded and as many as 30 others were found. No-one was hurt in the explosion.
One bomb was rigged to the petrol tank of a car in the school car park.
The gunmen opened fire at about 1130 local time (1730GMT), and were said to have targeted crowded areas, such as the canteen and library.
At least 28 people were injured and some remain in a critical condition. A girl is said to be in a "stable" condition after suffering nine gunshot wounds to the chest.
During the massacre, one blood-spattered pupil fell from a window into the arms of police officers. Another held a sign to a window which read: "Help me, I'm bleeding to death".
Police are understood to have traded shots with the two teenagers, before they killed themselves. Their bodies were found in the library.
Pupils at the school described the suspects as "militaristic", and there have been unconfirmed reports that one of the gunmen posted a warning about the massacre on his "hate-filled Website".
An unnamed friend of the gunmen told BBC News that they had "joked and bragged" about killing.
"I never thought that they'd do it. I never thought they'd go through with it," he said.
Three people, believed to be friends of the suspects, were arrested in a field near the school and led away in handcuffs.
A police spokeswoman said they were wanted for questioning and were not thought to be directly responsible for the shootings.