BERKELEY, Calif. (AP) — Officials say students at the University of California at Berkeley are still not being allowed back on campus following an explosion from a power outage.

A UC Berkeley spokesman says the explosion happened Monday evening in an underground electrical vault as power was trying to be restored on campus.

The explosion sent one person to the hospital with minor burns.

The spokesman says the blast may have been caused by an underground copper wire theft at a campus substation last week, causing more damage than initially thought.

Fire crews also rescued about 20 people who became stuck in dorm elevators when the power went out.

It's still unclear whether classes will resume on Wednesday.

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