CINCINNATI (AP) — A massive fire underneath a bridge spanning the Ohio River closed a heavily traveled route between Cincinnati and northern Kentucky on Friday and damaged part of the steel structure. No injuries were reported. The fire broke out overnight near a playground under the bridge, shutting down Interstate 471, according to the Cincinnati Fire Department. Video showed flames soaring more than 40 feet into the air and igniting a short section of the bridge, known for its yellow arches, near downtown Cincinnati. Chunks of concrete fell from the bridge and the fire warped a few of its steel beams, fire crews reported. The heaviest damage was on the bridge's southbound lanes leading to Kentucky and will take weeks to repair, said Matt Bruning, a spokesperson with the Ohio Department of Transportation. At least three beams and a section of the roadway will need replaced, he said. What caused the fire is under investigation, said Frank McKinley, the city's fire chief. The flames were fueled by mulch as well as plastic and wood playground structures below the bridge, he said. More than 60 firefighters helped bring the fire under control, he said.