Fire crews freed about 20 people trapped in dormitory elevators across campus as a result of the outage, said UC Berkeley spokesman Dan Mogulof.
The power outage was reported around 4:30 p.m. Monday and led to classes being canceled as students were told to suspend all lab activities, Mogulof said.
About a half-hour later, authorities reported an apparent ammonia leak in a room at Latimer Hall. It was contained almost immediately, campus officials said.
That was followed by an explosion in an electrical vault near California Hall shortly before 7 p.m., Berkeley acting fire Chief Gil Dong said. It occurred as crews tried to turn the power back on campus.
The explosion sent at least one person to a local hospital with non-life threatening injuries and a few others received minor injuries and refused treatment at the scene, Mogulof said.
The blast may have been caused by an attempted underground copper wire theft on campus last week, Mogulof said.
"It appears that may have caused far greater damage than initially thought," Mogulof said.
But officials said the cause of the other incidents, and whether any or all of them were related, had not immediately been determined.