A power outage and explosion at the University of California at Berkeley was connected to a theft of copper wiring.

The campus-wide power outage began at about 4:40 p.m. on Monday, and it was followed by an explosion and fire in an underground steam tunnel between California and Durant halls at about 6:40 p.m. that shrouded the campus in smoke, said CBS News.

The explosion led to a call for an evacuation of campus, and the resulting fire was extinguished by 8:15 p.m.

At press conference Tuesday afternoon on campus, UC Berkeley spokesperson Dan Mogulof announced that university officials had confirmed that the outage  stemmed from a theft of copper wiring sometime last week from an area about a half-mile east of campus.

The thieves stole copper wire from a remote underground vault using machinery that was so strong it flattened the normally round power cable, according to CBS News.

“We can confirm, at this point, that the damage done by the theft of copper cable was in fact responsible for the power outage,” said Mogulof.