ST. LOUIS (AP)-- A tow boat collided with a bridge Saturday, causing 15 barges to break free in the rain-swollen Mississippi River near downtown St. Louis.

The U.S. Coast Guard said the coal-loaded barges were being towed on the river when the collision happened around 11:30 a.m.

The breakaway barges bumped into other barges that were in a holding area as they drifted in the current. One of them sank and another became pinned against the bridge. The other 13 were contained within an hour, said Petty Officer Tom Atkeson, a Coast Guard spokesman.

The bridge that was hit and a one-mile stretch of the river have been closed. Officials are being sent to determine whether the bridge is safe, and plans are being made to remove the pinned barge, Atkeson said.

There have been no reports of pollution spills, but Coast Guard investigators also will determine whether any of the collisions with other barges caused dangerous chemicals to flow into the water, Atkeson said.

Although the cause of the bridge collision wasn't immediately known, the area has been deluged with rain.