"If they'd have been a couple seconds slower, they'd be dead ... no question," Mills said.
Both men were injured and were taken to University Hospital Burn Center in Salt Lake City, where Jenkins is in fair condition and Joseph is critical.
Mills found that someone had used a backhoe to reach a pipe about six feet below ground, and the teeth of the backhoe had scored the top of the pipe and weakened it. That pipe exploded when a pressure spike traveled through it Tuesday morning, creating a crater 15 feet deep and 30 feet wide.
The freed, surging gas connected with an ignition source and sent the station up in flames, Mills said.
Mills will submit his written report and the Occupational Health and Safety Administration will likely take over the investigation, he said.
The explosion does not appear to have discharged any hazardous materials beyond the site, according to a statement from Bill Barrett Corp., an oil and natural gas company that runs the station.
"This is a very difficult time for all of us," said Fred Barrett, chairman, CEO and president of the company, said in a statement. "Our thoughts and prayers are with our injured colleagues for their speedy and complete recovery from the injuries suffered from the fire."