Firefighters Battle Blaze at Marathon's Galveston Bay Refinery

Firefighters on Wednesday were battling a fire at Marathon Petroleum's (MPC.N) 593,000 barrel-per-day Galveston Bay Refinery in Texas City, Texas, a company spokesperson said.

"All employees have been accounted for and there have been no injuries," spokesperson Jamal Kheiry said in a statement.

The fire was continuing to burn within a sour water tank at the Power 2 unit in the refinery, said two people familiar with plant operations.

Production would not be affected by the fire, the sources said.

At about 4 p.m. CDT (2200 GMT) a fire was reported coming from a vent on a tank, which triggered an explosion in a second tank at the Power 2 unit, the sources said.

The firefighters are developing a plan to extinguish the fire that continues to burn in the second tank.

Kheiry said monitoring did not detect any impact on air quality outside the refinery.

The Power 2 unit provides utility water, fuel gas and steam to the refinery.

Sour water is wastewater produced in the refining process that contains chemicals such as hydrogen sulfide and ammonia.

The Galveston Bay Refinery is the fourth largest by capacity in the United States.

(Reporting by Erwin Seba; Editing by Jacqueline Wong and Stephen Coates)