GEORGETOWN, Colo. -- Federal investigators focused Thursday on working conditions and safety procedures inside the hydroelectric plant tunnel where five workers died after initially surviving a fire that erupted on the equipment they were using.

Autopsies were pending, meanwhile, to determine what killed the five men on Tuesday.

Authorities believe smoke and fumes likely killed the workers, who were trapped about 1,000 feet underground. Communication from the workers ended about an hour after the fire broke out.

The men, whose bodies were found scattered along a 200-foot length of the 12-foot-wide pipe, didn't have any burn marks, indicating that they probably died from the smoke and fumes from the chemical fire, said Undersheriff Stu Nay.

The dead RPI Coating workers were identified as Donald Dejaynes, 43; Dupree Holt, 37; James St. Peters, 52; Gary Foster, 48; and Anthony Aguirre, 18; all of California.

Gov. Bill Ritter toured the Xcel facility Thursday and met with the victims' families.

"We certainly are sympathetic to this absolute and awful tragedy and just offer anything we could in the way of assistance or help," Ritter said. The governor pledged to the victims' families that the incident will be thoroughly investigated and promised them that all of their questions would be answered.

He said that the families were devastated but appreciated the support from Colorado and the tight-knit community of Georgetown.

Family members who had flown into town refused comment Thursday when approached by reporters in a Georgetown hotel lobby. They are awaiting for autopsies to be completed before they can bring the bodies of their loved ones back home.

The victims' bodies were taken to the Jefferson County coroner's office in Golden for autopsies.

The Clear Creek Sheriff's Office released 911 calls as well, which were dramatic but didn't reveal any detail that hasn't been known.

In one tape, Bob McGurk, a Control Specialist at Cabin Creek is heard.

"We have a fire in our penstock, in our tunnel," he said. "I've got a chemical fire 1,000 feet underground... There are people trapped."

OSHA Looks Closely At Companies

Being looked at by OSHA: What kind of protection and safety training the maintenance crew had; safety procedures for the type of work being performed inside the tunnel; documents relating to the maintenance project; and documentation that safety procedures were being followed, said agency spokesman Rich Kulczewksi.

The OSHA probe was expected to take months and involve numerous federal, state and local agencies, said the agency's Denver area director, Herb Gibson.

"We want a thorough investigation that will ensure this type of incident will never occur in the future when people are working in confined spaces," Gibson said.

Investigators on Thursday were interviewing personnel from Xcel Energy, which operates the plant; RPI Coating Inc. of Santa Fe Springs, Calif., hired to apply an epoxy and paint coating to the inside of the tunnel; and KTA-Tator Inc., a Pittsburgh-based consulting and engineering firm whose work at the plant wasn't immediately clear.

Bruce Rutherford, KTA-Tator coatings business operations manager, declined to comment and referred calls to Xcel. The utility said it could provide no immediate information.

The California contractor that employed the five men who died in the plant fire had been issued numerous safety violations in the past, according to a California safety official.

RPI Coating was one of three contractors fined for safety violations that contributed to a worker's death in 2002.

At this point it's unclear whether that contractor will face any civil action and the victim's families just want to know more about what actually happened.

"He did a dangerous job. A job that not everybody would do," said Rick Foster, the brother of a victim.

"It's very hard not to know anything. We don't know where to go from here. We don't know what to plan for. We don't know anything," said Brandy Vincent, the victim's daughter.

Clearer Picture Of What Happened Forms

Nay said the blaze erupted while they were coating the tunnel with a mixture of paint and epoxy. The mixture is kept in a hopper to warm it up so it will flow through a sprayer. Nay said the workers were having problems spraying it and were adding a solvent to the hopper when the hopper's heating element inadvertently turned on, igniting the vapors.

When the fire broke out, the five workers scrambled past a bulkhead used to keep their work area dry. They radioed to their co-workers that they were OK, except for minor injuries, but fire blocked their downhill escape route. The steep 55-degree incline of the tunnel above them kept them trapped more than 1,500 feet below the ground.

The workers' radio went dead, and rescue crews lowered a spare radio and breathing masks to them. It wasn't known if the workers got those items.

Authorities defended their rescue efforts, saying smoke, the complexities of the 4,000-foot tunnel's design and uncertainties about the dangers delayed their entrance into the tunnel after the men for more than 3 1/2 hours after the blaze broke out.

Nay said one crew did attempt to go in about 1 1/2 hours after the fire broke out but had to turn back because of the thick smoke. Large fans, which had to be trucked in from Denver, were placed at the bottom of the tunnel to draw out smoke.

Nine RPI Coating employees had been sealing the inside of the pipe to prevent corrosion, a routine procedure that followed an annual inspection. An RPI employee outside the tunnel rushed inside and was injured while trying to help his co-workers.

Four workers escaped the tunnel, which delivers water from a reservoir to turbines that generate electricity at the Cabin Creek plant.

It wasn't known how long plant operations might be affected. Maintenance originally had been scheduled to last until mid-November, said Xcel spokeswoman Ethnie Groves.

Those wishing to provide assistance to the victims may donate to the Cabin Creek Relief Fund at Clear Creek National Bank. Call 303-567-9700 or visit the bank's Web site for more information.