UC Berkeley spokesman Dan Mogulof says the explosion occurred Monday evening in an underground electrical vault outside California Hall as power was trying to be restored on campus.
Mogulof says the explosion sent one person to the hospital with minor burns as three others also received minor burns but refused treatment.
The blast may have been caused by an underground copper wire theft at a campus substation last week causing more damage than initially thought according to Mogulof.
Fire crews have also rescued about 20 people stuck in dormitory elevators as a result of the outage that also led to a mandatory evacuation on campus.
It's still unclear when classes will resume.