The University of California at Berkeley evacuated the campus Monday night after an explosion  caused by a power system failure. One student with minor injuries was taken to the hospital, and four others with minor injuries declined to be hospitalized. Late Monday night, Berkeley officials told students they could return to housing units on campus. The power outage hit the campus at 4:40 p.m., and shortly after that evening classes were called off, and laboratories were told to shut down operations. About 20 people were stuck in various elevators on campus but they were all rescued by 8:30 p.m. The explosion took place about 6:40 p.m.