MAYES COUNTY, Oklahoma - An explosion and fire at the GRDA Power Station in Mayes County early Sunday caused minor injuries.

GRDA officials confirm the fire took place around 3:30 a.m. at the coal-burning power plant at 8142 Highway 412B near Chouteau.  Grand River Dam Authority spokesperson Justin Alberty said there were minor injuries as a result of the explosion. Three people were treated and released at the Pryor hospital for minor injuries following the explosion.

The incident was the result of some "construction-related activity" being performed by contractors on GRDA's Unit 2 coal-fired generator," he said.

No GRDA personnel or equipment was involved.

There was no structural damage to the plant, and the cause is still under investigation, Alberty said.

"The job site has been shut down as the investigation continues, although Unit 1 at the facility remains in operation," Alberty said.

GRDA broke ground at the first of this year on a major addition to the power station, a unit that will run on natural gas. The $425 million generator is being built on the east side of the power plant. GRDA CEO Dan Sullivan told News On 6 the new fuel source will be cheaper and better for the environment.

Construction on the natural gas unit started in March and is expected to take two years to finish.

Alberty said he expects to release more information when the investigation into Sunday's explosion is complete.