A stretch of the Ohio River near Pittsburgh remained closed to maritime traffic on Monday as crews equipped with sonar looked for a barge believed to have sunk over the weekend — one of more than two dozen barges that broke loose and floated down the river.

The U.S. Coast Guard launched an investigation into how 26 river barges got loose from their moorings late Friday, striking a bridge and causing extensive damage to a marina. All but three of the barges were loaded with coal, fertilizer and other dry cargo.

No injuries were reported and no hazardous materials spilled into the river, according to Pittsburgh police and Coast Guard officials.

The area had been hit by flooding after heavy rains Thursday, and Coast Guard investigators were looking at high water as a possible cause or factor, said Cmdr. Justin Jolley of the Coast Guard marine safety unit in Pittsburgh.