A large boulder broke off from the side of a hill and crushed four workers at a construction site on Tuesday in southwest China's Chongqing Municipality, killing three and injuring one, local authorities confirmed on Wednesday.

The workers were building a dining hall for the Central Primary School in the Miaoya Township of Wulong County at the time of the accident, which was shortly after 3:30 p.m., said a spokesman with the county government.

Three workers died during a rescue attempt. The survivor was sent to a medical center in serious condition.

The accident did not affect the students' safety, said the spokesman.

The cause of the cave-in is under investigation.

(Xinhua News Agency November 12, 2008)