Virginia ? A barge filled with more than 1 million gallons of hot liquid asphalt ran aground Monday, leaking 8,400 gallons into the James River, officials said.

Gerald Seeley Jr., a regional director of the state Department of Environmental Quality, said there was no evidence of any substantial damage to aquatic life.

The Coast Guard was investigating what caused the barge to run aground.

The accident happened before daybreak about five miles south of Richmond. One tank, holding 120,000 gallons of the 270-degree asphalt, sprang a leak. The other tanks on the barge did not appear to be leaking, the Coast Guard said.

Firefighters and hazardous-materials crews worked to contain the spill with booms. The spill area was about the size of a football field, authorities said.

The leak closed a milelong section of the river. The Coast Guard said cleanup of the spilled asphalt and salvage of the barge is expected to take several days.