At least three people were treated on the scene and one person with minor burn injuries was transported to a hospital following an explosion near California Hall on the University of California's Berkeley campus on Monday evening that has now been connected to an act of vandalism last week.

The explosion, which “was about two stories high and as wide as a two-lane street,” according to Berkeleyside, a local newspaper, took place at about 6.30 p.m. local time (9:30 p.m. EDT), and was caused by a power system failure. 

Students were immediately asked to evacuate the campus and according to Dan Mogulof, a campus spokesperson, 20 people who were stuck in elevators following the power outage were freed at about 8.30 p.m. local time on Monday.

Multiple police units, fire trucks, and at least four ambulances immediately responded to the incident, and according to reports, an ammonia leak suspected to be related to the power failure was immediately contained by the Berkeley Fire Department by 6:20 p.m.

Mogulof told the media that the explosion appeared to have been the result of vandalism that was noticed by university authorities over the weekend when the campus experienced some electrical problems following a copper wire theft. The damaged electrical lines were believed to have been repaired until there was another power outage on Monday.

"The explosion occurred when university engineers were bringing power back online," Mogulof was quoted as saying by NBC Bay Area. "It now appears the damage caused by these unknown individuals was far more extensive and far more significant than seen and assessed."

The power outage and explosion led to the cancelation of evening classes on Monday, and UC Berkeley said in a notification on its website that officials are evaluating the situation to determine whether classes will resume on Tuesday.