MIDDLETOWN, Conn. — Multiple people have died in an explosion at a power plant in Connecticut and an unknown number of people are injured.

Al Santostefano, the deputy fire marshal in Middletown, tells The Associated Press the explosion happened at 11:17 a.m. Sunday at the Kleen Energy power plant there and portions of the building blew away.

He says 50 workers were inside.

He and Betsy Hard, deputy commissioner of the state Department of Emergency Management and Homeland Security, say they do not know how many people were killed or injured.

Hard says Middletown authorities have asked surrounding communities for help, and urban search and rescue teams are on their way.