UPDATE, Friday, 8.35am: Police are appealing for information from the public after a fire was deliberately lit on the Wollaston pedestrian bridge on Thursday evening.
Detective Senior Constable Craig Wastell, of the Warrnambool police crime investigation unit, said he wanted to hear from anyone who saw something suspicious in the area just prior to 7pm.
"There was a heap of kids there swimming during the day but we've been told they left well before the fire was started," he said.
"The fire was reported by two kayakers who went past the bridge and when they returned 10 minutes later the fire was burning. They and some other kids reported the fire to emergency services."
Detective Senior Constable Wastell said the fire was clearly deliberately lit, probably with the use of an accelerant.
"Anyone who saw anything at that time is requested to contact the Warrnambool police station or Crime Stoppers on 1800 333 000," he said.
Warrnambool City Council officers will also inspect the bridge today for structural damage.
Thursday, 8pm: A quick response by firefighters at the Warrnambool fire station has helped save the heritage-listed Wollaston pedestrian bridge from being seriously damaged by fire.
Police are investigating the cause of the fire that charred a small section of one of the timber bearers that run lengthwise under the footbridge.
The fire was reported just before 7pm and the quick response by Warrnambool station members had it under control within four minutes.
Wollaston bridge is located less than a kilometre away from the Warrnambool fire station on Mortlake Road.
Three fire appliances attended.
Warrnambool senior station officer Travis Klein said the fire did not do much damage but Warrnambool City Council was called to check whether the bridge remained structurally sound.
The bridge was closed to pedestrians while authorities conducted their investigations but the Wollaston Road bridge remained open to traffic.
The Wollaston Bridge was built in 1890 and is one of Warrnambool's iconic landmarks.
It is one the oldest cable suspension bridges in Victoria and one of the most striking.
Spanning the Merri River, the bridge’s construction was privately funded, which was unusual at the time, and served as the entrance to the Wollaston estate.
Thirty metres long, the timber bridge is suspended on steel cables and anchored by four steel-capped stone pillars.
The cables used were recycled from the Hawthorn cable car, a cable tram that operated in Melbourne.
The bridge now caters exclusively for pedestrians with a new bridge built in 1967 adjacent to the 1890 bridge catering for vehicle traffic.
The state government earlier this year announced a grant of nearly $200,000 to help preserve the timber bridge.