Parts of the bridge, including wood beams, went up in flames. The fire also melted some AT&T communication lines that ran close to the bridge.
The police department says this is an ongoing problem with the homeless.
"We know that we have them under the bridge," said Sgt. Jason Cullum. "We do check on them. It's more of a welfare check to make sure they're okay. We don't necessarily want to run everybody out, unfortunately this event will bring that issue to the service. Should we allow them to stay under there at all?"
Officers say the bridge is okay to drive across.