WOODS CROSS — Firefighters and company officials have begun investigating the cause of a fire at a refinery here that seriously injured four workers and led to the evacuation of hundreds.

The South Davis Metro Fire Agency said the blaze at Silver Eagle Refining was extinguished about 4 a.m. Tuesday after more than 80 firefighters worked through the night to put it out.

"They did a really good job and worked very hard in hard conditions," said Jeff Bassett, deputy fire chief.

The fire at one of Silver Eagle's 420,000 gallon gasoline tanks injured four people, who remain hospitalized — one in critical condition, three in serious condition at University Hospital's burn unit, hospital officials said Tuesday.

"My friend was one of the many injured," someone posted at deseretnews.com. "He is in trauma right now."

In a statement Tuesday, refinery manager Kerry B. Carroll said two of those injured were employees of Silver Eagle — Alex Bloomfield and Phil McSwain. The other two were identified by authorities as Timothy Harter and Rob Benoit of Elite Insulation. Harter remains in critical condition, while Benoit is hospitalized in serious condition.

"All four individuals sustained second- and third-degree burns to their upper extremities," Carroll said.

An explosion at the refinery occurred about 5:30 p.m. Monday, injuring the four men and sending flames high into the sky. Residents within a half-mile of the refinery were ordered to evacuate to nearby Woods Cross High School. About 100 homes were affected.

"Our concerns were the tank failing or the tanks next to it getting too hot and catching on fire," Bassett said.

Firefighters from several agencies and nearby refineries helped put out the blaze. They have all had specialized training at refineries in College Station, Texas, and Reno, Nev.

In a late night "blitz" attack, firefighters smothered the fire with special foam they shot into exhaust vents of the flaming gas tank.

"We shot foam inside those vents," Bassett said. "We had to get enough foam to cover the entire surface area."

Investigators will be back at Silver Eagle to begin looking at the cause of the explosion. Workers at the refinery will be questioned, as will the four victims when they are able to communicate.

"We anticipate it's going to take a week to do interviews and figure out what happened," Bassett told the Deseret News.

The refinery will be working with fire investigators to determine the cause.

"This event had no significant environmental impact," Carroll said.