GEORGETOWN, Colo. — A chemical fire at a hydroelectric plant outside this mountain town 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, said Clear Creek County undersheriff Stu Nay said.

"We have found the parties. We have five fatalities," Nay said.

Xcel Energy spokeswoman Ethnie Groves had said the workers initially communicated they weren't injured after the fire broke out. They said they had rushed uphill to a section of the pipe blocked off to prevent ground water from seeping into it.

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.

Two of the four workers who scrambled out from the pipe were treated for chemical inhalation. One was airlifted to a hospital, Groves said.

The water tunnel had been shut down for routine maintenance.

The underground channel is called a penstock, which delivers water from a reservoir to turbines that generate electricity. The maintenance was being done by a contractor, but Xcel did not release the contractor's name.

The hydroelectric plant generates electricity during peak times of demand by releasing water from one reservoir into a lower reservoir, then pumping the water back to the upper reservoir.

It was built from 1964 to 1967 and is located about 2 miles southwest of Georgetown at 10,018 feet above sea level.