SOUTH BRISTOL, Maine — A barge cut loose from the dock by ice crashed into rocks in the Damariscotta River on Friday morning, causing an undetermined amount of oil to spill into the river.

The Maine Department of Environmental Protection, U.S. Coast Guard and other emergency agencies responded just after 9 a.m. and found the barge leaking oil at the Mook Sea Farm aquaculture facility, which cultivates oysters.

It was not clear Friday afternoon how much oil spilled, according to Coast Guard spokesman Connan Ingham. Maine DEP spokeswoman Jessamine Logan said the discharge was a mixture of oil and water.

The Bristol Fire Department contained the sheen within floating booms, and contractors Colby and Gale emptied the remaining fuel from the barge, according to Ingham.

The Coast Guard sent a 47-foot boat to secure a safety perimeter. The boat has since cleared the area, Ingham said.

The angle of the barge allowed water to enter the vent of the tank, displacing the liquid and causing it to be discharged into the river, Logan said.

The spill occurred across the river from Dodge Lower Cove, about two miles west of Bristol center.

Late Friday afternoon, Logan said the leak had been contained and the tank plugged. The barge remained on the rocks, and removal operations were scheduled to begin on Saturday.