Temporary generators have returned power to UC Berkeley after a power outage and explosion on Monday. Campus spokesperson Dan Mogulof said the power outage was a direct result of copper grounding wire theft from the campus’s electrical system.

An abrupt explosion shook the campus about two hours after it was left without power. The Daily Cal reports that firefighters began evacuations  after smoke and the fragrant smell of ammonia began seeping from two underground generators.

Four students sustained minor injuries from the incident. Whether there is a connection between the theft and the explosion is still being investigated.

On Tuesday night, temporary generators were installed and successfully illuminated almost all of the buildings and residence halls on campus and have also restored climate control for both Doe and Bancroft libraries, the home of important documents such as the Mark Twain papers.

“Repair work on the damage that was done by the explosion is already underway,” Mogulof said. “The generators are supplying power and we’re just going to take as much time as it requires to do it right and do the repairs safely.”