An emergency warning has been issued for communities on Melbourne's south-western fringe after a suspicious grassfire broke out in hot conditions.
The CFA said people who live in Manor or Mambourin, near Werribee, should evacuate immediately.
Video from the scene shows some structures have caught on fire.
CFA incident controller Geoff McGill said the fire was being treated as suspicious and appeared to have three points of origin.
He said investigators would look into those locations when it was safer.
"We'll be treating them as suspicious," he told ABC Radio Melbourne.
"I don't want to make any assumptions at this stage … but yes it is disappointing if it's found out to be deliberate."
A relief centre has been set up at Centenary Hall in Norlane.
CFA operations officer James Dullard said the fire authority had requested 50 fire tankers attend the fire, with 35 already on the scene.
"We have some vision of some sheds that have been impacted," he told ABC Radio Melbourne.
"No sign of any houses [on fire] — there's been some good work to save some houses looking at the vision.
"We have aircraft that is operating from Avalon and we're trying to establish a significant break along the rail line."
The emergency warning said people should travel to a safer location, and if they were away from home, not to return.
People should take pets, mobile phones and chargers with them, it said.
It is believed the fire started in a paddock. Already, more than 600 hectares have been burned.
A separate advice message was issued for residents of surrounding communities, including Brophy's Crossing, Cocoroc, Little River, Mambourin, Tarneit, Werribee and Wyndham Vale.
The fire was travelling in a south-easterly direction and was burning on both sides of Edgar's Road towards Manor Road.
Residents meet after Buninyong blaze
Victorian firefighters have been bracing for hot and windy conditions across the state today.
Extra crews have been sent to help out after a bushfire emergency near Ballarat in western Victoria yesterday, and another fire in the state's east.
A total fire ban is in place for much of the state's north and west after firefighters continued to battle blazes at Buninyong and Seacombe in sweltering conditions overnight.
The Bureau of Meteorology (BOM) said the temperature did not drop below 26 degrees Celsius overnight in Melbourne and remained in the high 20s for most of the night.
An emergency warning was issued for the Buninyong fire before it was finally brought under control about six hours later.
Emergency Management Commissioner Andrew Crisp said the Buninyong blaze was in heavily forested country and "tested" fire officials.
"We put significant resources [on the fire] … and we've got large air tankers now that are on contract that only started a couple of days ago," Mr Crisp told ABC Radio Melbourne.
"That's why it was pulled up as quickly as [it was]."
More than 100 firefighters continuing to do black-out work today were trying to strengthen containment lines around the fire to prevent any flare-ups.
This morning, about 200 residents turned out for a community meeting at the Buninyong Town Hall.
Incident controller Ben Boatman told the meeting the fire had been intense from the beginning.
"Our message to people today is don't do anything that could cause the next fire and stay alert please," he said.
The hot and windy conditions were not expected to ease until late this afternoon.
'We were going to lose our place'
The community is still recovering from the 2015 Scotsburn fire, which destroyed 19 homes.
Buninyong resident Craig Morey, who had to evacuate yesterday, said the fire was about a half a kilometre from his home.
"I rang my wife who was at home with my daughter and my daughter's friend and told them to quickly grab some things and get out," he said.
"It just spread so quick, it looked like it was coming towards us.
"I accepted we were going to lose our place, looking at how fast it was going — but it managed to stop at the corner of our block.
"I've never seen such a quick response by the CFA. It was incredible."
A watch-and-act warning remains in place for Durham Lead, Grenville and Scotsburn, near Buninyong, ahead of forecast difficult conditions today.
"It's hotter and it will be windier," said Mr Crisp.
"Today we're certainly ready, we've got incident control centres set up across the state, we've got our resources ready to go."
There are total fire bans in place for the Mallee, the Wimmera and the North Country, with temperatures rising above 40C in parts of the state.
Firefighters worked through the night to contain a bushfire in coastal scrub near Seacombe, on Lake Wellington, east of Sale in eastern Victoria.
The fire started at 4:15pm on the Longford-Loch Sport Road and burnt 70 hectares of farmland and coastal scrub.
CFA operations manager Alan Rankin said crews were on deck to prepare for flare-ups in today's forecast hot conditions.
"At the height of it yesterday, we did have two fire-bombing aircraft from Bairnsdale come up and we did have a fire-bombing helicopter from Heyfield as well, so they were fantastic assets to support our ground crews," he said.
Blaze scorches farmland
Seacombe farmer Rolland Troedel said sections of his farm were burnt but he managed to save his livestock.
"So our perimeter fencing is ruined. I did have some sheep in the paddock so I have had to move them out of there to somewhere safe," he said.
"From what I can tell it started next to the road. I've got a feeling someone threw a cigarette out of their window."
Loch Sport resident Trish drove past the fire and told ABC Gippsland it looked like it started on the side of the road.
"It was ablaze on the side of the road and at that time it was just going back into the bush and then I drove back again at 10:30pm and it was horrific going all along the road."
Melbourne was expected to hit a peak of 38C around 5:00pm.
"I just want to urge people to, if they see suspicious behaviour, to report it to police," said Mr Crisp.
"Be conscious about what people are doing out there.
"Last weekend fires started as a result of people not attending to campfires, use of machinery, those types of things.
"There are simple things that people can do to support us and to support our communities."ABC