The U.S. Coast Guard says it is working to free a tanker that has run aground in shallow water in the Gulf of Mexico 22 miles off the coast of Galveston, Texas.

Coast Guard spokeswoman Renee Aiello says the 800-foot tanker is carrying 620,000 barrels of an unknown fuel.

She says the crew of a Coast Guard helicopter has flown over the ship and seen no evidence of a fuel spill.

Aiello says the Yasa Golden Dardanelles ran aground sometime Friday while waiting for a pilot to guide it into the Houston Ship Channel.

Officials from the Coast Guard are working with other federal and state agencies and a salvage company to plan a strategy for freeing the vessel.