The Coast Guard said in a news release the oil spill occurred Saturday when a barge collided with another vessel near Vacherie, between New Orleans and Baton Rouge.
"Lightering operations on the damaged barge concluded early Sunday morning and the source of the spill was secured," the release said. "Oil spill response vessels and recovery equipment are deployed in the river."
The Coast Guard said the Captain of the Port closed the river from mile marker 90 to mile maker 155 "to avoid possible contamination of passing vessels and to reduce the amount of oil spreading further down the river."
A Coast Guard Air Station New Orleans MH-65 Dolphin helicopter crew assessed the situation late Saturday and was scheduled to fly over the scene against Sunday night, weather permitting.
A unified command including the Coast Guard, the Louisiana Oil Spill Coordinator's Office, the environmental cleanup company ES&H and the Louisiana Department of Environmental Quality was cooperating on the response to the spill, the Coast Guard said.