The GRDA in Tulsa is investigating an explosion at the Kerr Dam and still trying to figure out exactly what led up to it; natural gas may have been a factor.
Three subcontractors with a Colorado company called D.A. Smith Drilling were working on a scouring problem on the dam Thursday night, which was caused by flooding over the years.
GRDA said they were also investigating gases detected in a 95-foot vertical tunnel.
The GRDA said preliminary results show pockets of those natural occurring gases may have contributed to the explosion, which trapped two of the workers.
They said the third man was higher up in the tunnel and able to escape with only minor injuries.
The bodies of both men who died were recovered Friday.
OSHA will conduct their own investigation on behalf of D.A. Smith Drilling.
News On 6 reached out to that company but has not hear back yet.