Crews work to clean up mineral oil spill in Ark.

FORT SMITH, Ark. (AP) -- The Environmental Protection Agency says crews are working to clean up a mineral oil spill in western Arkansas.

EPA spokeswoman Jennah Durant says Monday that officials discovered the spill on Saturday after a transformer apparently fractured at an Oklahoma Gas and Electric substation in Fort Smith. The utility is a unit of OGE Energy Corp.

Durant says officials are working to determine the extent of the spill and whether any oil reached nearby Massard Creek.

Durant says the oil has been contained, though it's not clear what caused the spill in the first place.

Durant says they haven't received any reports of injuries related to the spill. Durant says mineral oil is highly refined and almost looks like cooking oil.

A spokeswoman for Oklahoma City-based OG&E didn't immediately respond to a phone message left Monday.