UC Berkeley Explosion - a two-storey high and two-lane street-wide explosion occurred at the University of California Berkeley Monday; one reportedly injured while 20 got trapped in elevators, CNN reported Tuesday.

An explosion at the underground utility vault of the University of California Berkeley injured one and trapped 20, triggering a campus-wide evacuation Monday night.

KTVU.com reported the explosion happened following a power system failure around 4:40 p.m. local time. College Spokesman Dan Mogulof said the incident was related to an attempted underground copper wire theft a week ago, when thieves used certain equipment to dig up and steal copper lines from the utility vault.

"The explosion was about two stories high and as wide as a two-lane street," Mogulof told the Associated Press. "We're very fortunate there were no serious injuries."

Newsmax reported that the injured individual was rushed to a hospital after refusing to receive initial treatment for the wound she obtained out of the UC Berkeley explosion.

The power was restored around 7 p.m. Monday night and classes resumed Tuesday morning, according to Fox News.

Aside from the injured individual, nearly 20 people got trapped inside campus elevators after the blast. They were freed only when the officials responded a couple of minutes later.

Meanwhile, campus officials said an ammonia leak in a classroom was discovered ninety minutes after the explosion, adding that it was contained right away.

Additionally, the explosion caused several students to panic since they had to compromise despite their upcoming midterms.

"I have midterms tomorrow as do a bunch of other students on campus," UC Berkeley Freshman Kelsie Carlson told KTVU. "A lot of students don't have power to study or get their laptops on or anything like that."

The investigation on the cause of the UC Berkeley explosion is still on-going although authorities initially said it was triggered by the copper wire theft last week.