LANZHOU - Seven people were injured after a gas blast rocked a student dormitory at a northwest China university on Monday morning.

The blast occurred at about 8 am at Lanzhou University in Lanzhou, capital of Gansu province, seriously damaging three floors of a 6-floor dorm building for continuing education students, according to fire fighters and Xinhua reporters at the site.

Five students and two staff members of a nearby hotel were among the injured.

"I heard a loud bang and saw the window glass broken, the door lock shaken open, and a group of shirtless students rushing out of the building," said a woman surnamed Ma who lives in a neighboring community.

The cause of the blast is still being investigated.