(CNN) The collapse of a concrete beam from a bridge in Chattanooga, Tennessee was likely caused when a vehicle carrying an oversized load hit the bottom of the bridge, a state transportation official said Tuesday.

The vehicle went under the bridge and sliced through some of the steel reinforcement strands in the exterior beam, Paul Degges, the department's chief engineer, told reporters. A concrete rail helped support the damaged beam but ultimately it collapsed, he said.

"We don't believe that the failure of the beam was an issue with the design of the bridge or maintenance activity," Degges said.

He said officials don't know who hit the bridge. The department's cameras don't keep a recorded history of footage, he said.

One person was injured after the concrete railing section fell from the bridge on Monday, shutting down two interstate ramps.