Officials in the Connecticut town where a power plant explosion killed five and injured more than two dozen people on Sunday, say all workers are now accounted for.

Middletown, Conn. Mayor Sebastian N. Giuliano and Deputy Fire Marshal, Al Santostefano said Monday no one is believed to be buried in the rubble.

Search operations were suspended at 2:30 a.m. Monday when rescue teams deemed the sight too unsafe to enter. 

Officials said the blast happened Sunday morning at Kleen Energy Plant as workers purged a natural gas line. 

State and federal officials are launching an investigation in to what caused the explosion. The U.S. Chemical Safety Board (CSB) said it is sending a seven-person team the energy plant today.

“The CSB’s investigative team will examine the activities that were ongoing at the time of this accident, including any gas purging,” Don Holmstrom, CSB’s lead investigator, said in a written statement.

Kleen Energy Systems said on its website the plant, which is still under construction and was expected to go online this summer, would be one of New England’s largest power plants, producing 620 megawatts of power.