A massive fire under a bridge over the Ohio River closed the heavily traveled route between Cincinnati and northern Kentucky on Friday and damaged part of the steel structure. No injuries were reported.

According to the Cincinnati Fire Department, the fire broke out overnight near the playground under the bridge and Interstate 471 was closed.

Video shows flames rising more than 40 feet into the air and igniting a short section of the bridge known for its yellow arches near downtown Cincinnati. Fire crews reported that chunks of concrete fell from the bridge and the fire warped some of the bridge’s steel girders.

The heaviest damage occurred on the southbound lanes of the bridge into Kentucky and will take weeks to repair, Ohio Department of Transportation spokesman Matt Bruning said.

At least three beams and a section of the roadway will need to be replaced, the official said.

Frank McKinley, the city’s fire chief, said what caused the fire is under investigation. He said the flames were caused by mulch under the bridge as well as plastic and wooden playground structures.

More than 60 firefighters helped bring the fire under control, the official said.