New York blast 'not terrorism'

Some reports say a boiler blew up next door

At least 50 people have been injured - at least three seriously - after an explosion at a building in New York.

The blast caused part of an eight-storey school to collapse, sending glass and debris flying.

Emergency services rushed to the scene on the corner of West 19th Street and 6th Avenue in the Chelsea district and sealed off the area.

Firefighters managed to pull many people from the rubble.

First reports suggested the explosion happened at the Apex Technical School, but latest reports say a boiler blew up in the basement of a building next door.

The BBC's Jane Standley, who is in New York, says officials are not treating the blast as a terrorist incident.

Floor collapse

Alan Awol, who was visiting the school, said one of the floors had given way.

Many suffered cuts and burns

"I heard a big explosion. The whole third floor had collapsed. People were stuck on the third floor. They looked like they were hysterical, like they wanted to jump out," he said.

Scott Bonilla, a student at the school, told the Associated Press news agency he was inside the building when it began shaking.

"They told us to rush out of the building," he said.

A school official said all students in the college were safely evacuated.

People who had been lightly hurt were treated on the pavement, while at least half a dozen other casualties were taken away by ambulances.

New York has been on edge since the 11 September attacks and the FBI has issued several warnings about possible further targets of attack.