VICKSBURG, Miss. — The Coast Guard said Tuesday that about 7,000 gallons of crude oil were unaccounted for aboard a leaking barge that had rammed a railroad bridge near Vicksburg on the Mississippi River, which remained closed for a third day as crews slowly pumped out oil.

Petty Officer Third Class Jonathan Lally said it is not clear that all of the 7,000 gallons leaked into the river. Some of it, he said, could have seeped into spaces inside the barge.