Renton fire officials are investigating a series of small fires set this weekend near the Cedar River Trail.

According to Renton Fire Marshal Anjela St. John, three small fires this weekend appear to have been intentionally set and investigators believe two of them to be related.

The most damaging of the fires was set under the Williams Avenue bridge at 5:30 a.m. Monday and caused damage to a conduit of wires that run along the side of the bridge. St. John said that a flare or firework of some kind was used to light that fire.

Damage is estimated to be around $5,000.

The Williams Avenue bridge also houses a natural gas pipeline near where the fire was set, but St. John said this weekend’s fire was not large enough to worry fire crews about its proximity to the pipeline.

In addition, city crews notified fire officials on Monday of a burned area around the base of a utility pole in the 100 block of Williams Avenue North. St. John said someone appears to have taken garbage from a nearby trash container, piled it around the base of the pole and then lit it on fire.

While the fire was apparently not large enough to warrant a call while burning, St. John said damage is estimated at about $1,000 and the city is looking into whether the pole, which is now charred, will have to be replaced.

A third fire was also set on Saturday in a plastic garbage can across the street from the utility pole fire. The trash can has since been removed. St. John said because of the proximity, officials believe the pole and trash can fires are connected, but are unsure of the fire under the bridge.

Earlier this year, the city experienced a spate of small fires in garbage cans and other areas around the downtown core, but St. John said the person responsible for those fires was caught and is still in jail, making it unlikely they are connected.

In addition to the fires, there was also some vandalism along the trail, including a broken window at the Senior Activity Center.

St. John said the investigation in still active and officials are still looking into the fires, including the possibility of video footage in the area around the bridge.

“We’re still looking to see if there’s other evidence,” she said.