Bendigo police are appealing for anyone with information to come forward after 12 fires broke out in the state's north on Friday.
The first fire started about 3.30pm in Goornong on the Elmore-Barnadown Road near Ellis Road.
A few minutes later, another fire started about a kilometre north on the Elmore-Barnadown Road near Lanmore Road. That fire burnt more than 70 hectares of paddock and a hay shed.
At its peak, there were 25 Country Fire Authority units responding with support from Forest Fire Management Victoria crews, two firefighting helicopters, and private units.
About 3.50pm, another fire broke out on McManus Road in Colbinabbin. About 10 minutes later, another grass fire started in Curr Road, Girgarre.
Another six fires broke out late on Friday evening.
About 10.30pm, CFA crews were called to a small grass fire on the Midland Highway in Carag Carag.
Read more: Firefighters declare Goornong fire safe
At 10.45pm, another fire started further down the highway in Corop.
A few minutes later, another small grass fire started on the Northern Highway in Elmore, near the site of the Elmore Field Days.
Police say another fire broke out quickly after on the Midland Highway in Burnewang, near McKenzie Road.
About 10.50pm, another blaze broke out on the Northern Highway in Runnymede near Capewell Road.
CFA crews were then called out to a fire about 11.10pm on the Northern Highway, Tooleen near the Cornella-Tooleen Road.
At 11.45pm, a fire broke out on the Axedale-Tooleen Road in Axedale, near the McIvor Highway.
A few hours later, at 1.10am, a fire broke out on Kangaroo Gully Road in Kangaroo Flat.
Bendigo Detective Senior Constable Andy Heazlewood said the fires were all small grass fires that were contained.
"They were not as big as the main one in Goornong," he said. "But they had the potential to be larger if the winds had not died down."
Police have been told a vehicle similar to an XD model Ford ute with a light bar was seen near the scene of one of the fires.
Investigators would be attending the fires on Saturday to determine their cause, Detective Senior Constable Heazlewood said.
He urged anyone with information to contact Crime Stoppers on 1800 333 000.
"Even if a witness saw a truck spark the fire, that is as helpful to us as someone saying they say someone deliberately light it," Detective Senior Constable Heazlewood said.
"Anything you see could be helpful to investigators."
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