VICKSBURG, Miss. — Cleanup crews with booms skimmed oily water from the Mississippi River a day after a barge with more than 80,000 gallons of oil struck a railroad bridge near Vicksburg, spreading a sheen of light crude that kept part of the waterway shut to ship traffic Monday, authorities said.

It remained unclear Monday morning how much oil had leaked into the river, according to the Coast Guard and Army Corps of Engineers.

The spill backed up at least 24 tugboats, barges and other vessels on the normally bustling corridor, said Kavanaugh Breazeale, spokesman for the U.S. Army Corps of Engineers in Vicksburg.

Breazeale said the damaged barge had eight tanks and each tank could hold 80,000 gallons of oil. He said the investigation had shown that one tank was pierced above the water line.

“It’s not leaking that much oil,” Breazeale said, though the exact amount was not known.

He also said it was uncertain how long the river would remain closed.