SAULT STE. MARIE, Mich. — The U.S. Army Corps of Engineers says it has refloated one of its tug boats that sank while being towed in the upper St. Marys River.

No one was aboard the Hammond Bay, which went down in the waterway between Michigan's Upper Peninsula and Canada. Another tug was towing the Hammond Bay and three barges from Duluth, Minn., to Sault Ste. Marie, Mich., at the time.

Army Corps spokeswoman Lynn Rose says the agency sent three vessels to the scene. She says they raised the tug to the surface and refloated it Wednesday afternoon.

She says there's no obvious sign of damage to the tug, which will be examined to see what repairs are needed.

The tug was in about 37 feet of water, about 290 miles northwest of Detroit.