Up to 18 homes are believed to have been destroyed in bushfires across Victoria’s south-west that have also killed livestock and razed pastoral properties.

Authorities welcomed a cool change on Sunday night that they hoped would ease conditions for more than 700 firefighters tackling active bush and grass blazes.

Victoria’s emergency management commissioner, Craig Lapsley, said the main concerns were fires at Cobden and Penshurst, where watch-and-act alerts remained active on Monday morning.

“We’re getting on top of the fires,” Lapsley told Nine Network on Monday. “The winds are down. The day’s a milder day. The temperature backed off. Today will be a good day in that sense.”

A house destroyed in the bushfires south of Cobden. Photograph: David Crosling/AAP

About 1,700 properties were still without power and Lapsley warned those affected might have to make do for a bit longer because power poles and other infrastructure had been damaged. “To restore the power is a big issue in some parts of those fires,” he said.

Warrnambool’s incident controller, Russell Manning, said his team would try to bring the eastern edge of the fires under control on Monday with six fire-bombing aircraft and two helicopters to help.

A team of 16 vets would also work in the area to assist animals hurt in the fire.

More than 400 people and 47 vehicles were preparing to help the Colac incident control centre tackle the fires between Terang, Garvoc and Camperdown.

Hundreds of beef and dairy cattle have been killed and about 40,000 hectares of prime pastoral and other lands burnt out.

About 800 people sought shelter at evacuation centres and many were still there on Monday.

Jo Beard, the mayor of Corangamite shire, which covers the Cobden area, said residents and farmers were trying to be brave as they waited to hear the extent of the damage.

“It’s been devastating, honestly, particularly on the farmers who have been through so much in the last couple of years,” she told Nine Network. “It’s a massive hit. It’s such an unknown how this will play out. We’re all still very much on edge.”

It’s believed not all of the homes destroyed were occupied. There have been no reports deaths or of people missing so far.

The state government will provide immediate personal hardship payments, worth about $1,900 a household, to use for food, clothing and shelter, with assessment for further support.

Police and fire investigators have yet to determine the cause of the fires, which began on Saturday, but authorities said it was likely to have been lightning strikes.

Homeowners with insurance caught in the fires will be given priority for their claims after the Insurance Council of Australia declared the fires a catastrophe on Sunday night.