The Occupational Safety and Health Administration Monday said RPI Coating "willfully" violated numerous safety codes by using a flammable solvent in the proximity of electrical equipment, including hot burning halogen lamps and heaters.

There was no escape plan and no fire extinguishers nearby, the report said.

"This catastrophe could have been avoided if the companies had followed their critical safety procedures," said assistant U.S. Labor Secretary Edwin Foulke Jr. in a statement.

OSHA cited RPI Coating with 40 violations and announced a fine of $845,100. Xcel was cited for 20 violations and fined $189,000.

The OSHA report did not name the cause of the fire, which trapped workers in a 1,400-foot deep tunnel, but cited many possibilities.

Xcel Chief Executive Dick Kelly said in a statement Xcel disagreed with the characterization "that implied we acted without regard to the safety of our employees and contracted workers."

Clear Creek County District Attorney Mark Hurlbert has been waiting for the OSHA report before proceeding with possible criminal charges based on the incident, The Denver Post reported.