Students at Columbine High School and nearby suburban Denver schools in the United States were told to stay inside because of a bomb threat that has drawn a large police response.
A spokesman for the Jefferson County Sheriff's Department, Mike Taplin, said that a person called them on Thursday morning, claiming to have placed explosive devices in the school and to be hiding outside with a gun.
Taplin says nothing to validate the threat was found at the school, where 12 students and a teacher were killed by two students in 1999.
He says the school receives many threats annually and that the police response was appropriate.
The school district says all doors have been locked at the schools but that classes are continuing normally.
