Colorado ? A chemical fire at a hydroelectric plant outside Georgetown killed five workers trapped 1,000 feet inside an empty water tunnel on Tuesday, authorities said.

Crews went in from the bottom of the tunnel to put out the fire and found the workers’ bodies, Clear Creek County undersheriff Stu Nay said.

Xcel Energy spokeswoman Ethnie Groves had said the workers initially communicated they weren’t injured after the fire broke out.

They were among a group of nine workers who were in the tunnel when a machine used to coat the inside of the 4-foot-wide pipe with epoxy caught fire, Groves said.

Four workers below the fire were able to scramble out of the bottom of the tunnel, which goes through a mountain to a small reservoir.