PORT SULPHUR, La. (AP) _ A tanker spilled 546,000 gallons of crude oil, closing traffic to a 26-mile stretch of the Mississippi River on Wednesday. No injuries were reported.

The 800-foot Westchester lost power Tuesday evening and apparently ran aground about 60 miles south of New Orleans, said U.S. Coast Guard Lt. Charles Culotta. The cause of the spill was not known.

A cargo tank lost about 13,000 barrels of Nigerian sweet crude, Culotta said. A standard barrel contains 42 U.S. gallons.

Closures stretched from the accident site to near the mouth of the Mississippi River. Contractors worked to contain and clean up the spill.