(CNN) -- Authorities on Wednesday recovered the bodies of five contractors killed after a fire broke out in the empty water tunnel they were working in at a hydroelectric generating plant near Georgetown, Colorado.
The bodies were not burned, Clear Creek County Undersheriff Stu Nay told reporters. They had no signs of trauma, suggesting they died from inhaling "noxious" smoke or fumes.
They were taken to the Jefferson County Coroner's Office in Golden, Colorado, authorities said.
Officials identified the dead were identified as Donald De Jaynes, 43; Dupree Holt, 37; James St. Petters, 52; Gary Foster, 48; and Anthony Aguirre, 18. All were from California.
The victims all were employees of RPI Coating of Santa Fe Springs, California.
The federal Occupational Safety and Health Administration was investigating the incident, along with the Colorado Bureau of Investigation, Nay said.
The workers were applying an anti-corrosive epoxy coating inside a penstock, or pipe, about 1,500 feet underground at Xcel Energy's plant when the fire broke out Tuesday around 2 p.m. MT (4 p.m. ET), Xcel spokesman Tom Henley said. The Cabin Creek Station plant is about 30 miles west of Denver. Watch the company spokesman describe the rescue attempt »
Four other workers managed to escape alive, two of whom were treated for chemical inhalation, Xcel spokeswoman Ethnie Groves said Tuesday.
The five workers who died were in a section above the fire and had scrambled about 1,400 feet away from it, Nay said. The bodies were found about 2,500 feet underground, he said. See a diagram of the tunnel »
About a half hour after the first call about the fire came in, some kind of verbal radio contact was established with the five contractors in which they indicated they were not seriously injured, Nay said.
Crews dropped fresh-air tubes and masks down into the tunnel so the workers could avoid inhaling the toxic fumes from the fire, but it's not known if they ever received the equipment, Nay said.
Crews discovered around 8:30 p.m. that the fire had gone out on its own, the undersheriff said.
The mine rescue team that eventually found the bodies ran an electrocardiogram on the victims and determined they were dead, Nay explained.
The contractors had begun the scheduled repair work inside the tunnel September 4 and were hoping to finish up in November, Henley said.
Calls to RPI Coating by CNN were not immediately returned.
Tim Taylor, president and CEO of Xcel's Public Service Co. of Colorado, said Tuesday the firm was saddened by the deaths and "certainly we'll be working closely with the authorities to investigate what happened." E-mail to a friend
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