2 Contract Workers Die in Explosion at Oklahoma Dam: 'It's a Tough Day'

Two workers are dead following an explosion at an Oklahoma dam, according to officials.

John Wiscaver, the executive vice president of strategic communications at Grand River Dam Authority (GRDA), confirmed the fatal incident at Kerr Dam during an interview with ABC affiliate KTUL.

Though the contract workers have not yet been identified, Wiscaver told the outlet that both men were Colorado residents and had been employed by DA Smith Drilling Company.

The DA Smith Drilling Company, which is based in Grand Junction, Colorado, did not immediately respond to PEOPLE's request for comment.

"It's a tough day and our hearts go out to those families," Wiscaver said during the interview. "It's, unfortunately, a situation we hate to see occur, but did occur."

The explosion happened on Thursday evening at around 6 p.m. while the contract workers were performing core-sample drilling on the dam as part of its routine safety maintenance program, Wiscaver told KTUL.

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At some point during the job, the workers discovered that there were some gases below the ground — something Wiscaver said was "not that unusual," but something the workers wanted to address.

While they were looking into the situation, it is believed that the men hit a methane gas pocket, causing the explosion to occur, KTUL reported.

The two workers, who were approximately 80 feet below the surface, then became trapped inside the shaft alongside a third employee, according to the outlet.

On Thursday evening, emergency crews managed to rescue the third contractor, Justin Alberty, a spokesman for the GRDA, confirmed to KTUL.

The worker — whose identity has also not been released — initially declined medical treatment but was later taken to a hospital for evaluation.

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As for the other two men, their bodies were recovered around 4:30 a.m. on Friday, according to KTUL, citing a statement from the GRDA.

Wiscaver told the outlet that it took several hours to pull the bodies from the shaft because officials had to ensure that nothing else would explode during the recovery process.

"GRDA appreciates the assistance it received from area emergency response and fire departments, including Tulsa FD's Technical Rescue team and Claremore FD's HazMat team, who helped with recovery," their statement added.

At this time, it is unclear what caused the explosion. An investigation into the incident is currently underway, the GRDA noted in their statement.