UC Berkeley's main campus was evacuated Monday night after a campuswide power outage disrupted evening activities and a generator explosion caused a few minor injuries.

The power outage began at about 4:30 p.m., and the explosion, which was caused by the power outage, occurred about two hours later on the north side of California Hall, said spokesman Dan Mogulof. Shortly thereafter, mandatory evacuations began.

The explosion sent one person to the hospital with minor injuries, Mogulof said. About four or five others experienced minor burns from the fire but were treated at the scene.

Mogulof said authorities were investigating the possibility that the outage and explosion were caused by a copper theft in Berkeley last week.

"The damage that could be seen and assessed was repaired over the weekend, but it now appears that the damage caused by the unknown vandals may have been far more extensive and may have been the cause of what happened," he said.

The power outage trapped about 20 people in elevators around campus, but they were all freed by 8:30 p.m., Mogulof said. The outage also caused a small ammonia leak at Latimer Hall, but it was contained almost immediately.

Sophomore Jay Reddy, 19, was in the basement of Cory Hall when he suddenly sniffed a "very pungent smell."

"The lights just went out," he said. "People were a little bit confused, people were wandering around, trying to find their way out. The emergency lighting came on, and there was limited lighting in the stairwell, but people were able to get out."

Evening classes were canceled and laboratories were closed. Many of the school's dormitories are powered by the central campus' electrical system and were also without electricity Monday night.

Mogulof said the businesses around campus still had power, and many students flocked there after they were evacuated.