PORTLAND, Maine (AP) — The U.S. Coast Guard says two tugboats collided off the Maine coast and one of the vessels sank as it was being towed back to shore.

Officials say one of the tugboats was towing the other when the vessels collided about three miles south of Kennebunk on Wednesday. No injuries were reported.

The Coast Guard escorted the 40-foot Helen Louise and its two crew members safely into Portsmouth, New Hampshire.

Another Coast Guard ship attempted to tow the 80-foot Capt. Mackintire to Portland, but the boat started taking on water. The Coast Guard crew cut the tow line and the unmanned vessel sank in about 160 feet of water early Thursday.

Authorities are still trying to determine how much fuel might have been spilled.