A team from the U.S. Chemical Safety Board is in Utah today to investigate Monday night's refinery fire in Woods Cross.
Silver Eagle Refinery officials say they believe fumes leaking under a storage tank were ignited when they spread to a nearby furnace. That could be to blame for the blast that injured four workers. Those men were doing maintenance right next to the tank when it caught fire, and they had to run through flames to escape.
Doug Harter, a brother of one of the victims, said, "My brother was one that fell down. They actually, to get away from the fire, they had to go through it. That's how they got the extensive burns."
One of the men injured in the explosion remains in critical condition while the three others have been upgraded to serious.
A full investigation into what happened could take weeks to complete.
The Deseret News reports Silver Eagle has been cited by the Occupational Safety and Health Administration 13 times since 2002, for what are considered "serious" violations. It has received a total of 23 citations in that time.
In 2005, one violation came with the most serious rating OSHA can give. It involved process safety management of hazardous chemicals.
The company won't comment on specific violations, but it says it tries to comply with OSHA and even hired a full-time safety expert this past year.