A big clean-up is underway in Ballarat in central Victoria, where a storm has brought down trees, damaged houses and caused flash flooding.
The State Emergency Service says it dealt with around 230 calls for help, mostly in the suburbs of Sebastopol and Mount Clear, when the bad weather swept through last night.
The storm brought large hailstones, strong winds and heavy rain.
More than 2,500 homes and businesses in central and western Victoria are without power.
SES spokesman Lachlan Quick says the wild weather tore the roof off properties and brought down trees.
"There's a palliative care facility in Sebastopol that had all 20 skylights broken and their power cut off [and] there were a number of properties that have had their roofs torn off," he said.
"[There are] a lot of trees down over roads, and certainly a lot of building damage to properties, with the high winds actually ripping the roof off a couple of properties in those suburbs.
"The damage calls were coming in at a rate of three or four a minute for probably close to an hour. We don't very often see that sort of rate of calls coming through."
Mount Clear resident Rob Hughes says the wind and rain came in a violent burst.
"It was like a mini-tornado just came through," he said.
"It was that quick, brought trees down, there are houses with roofs off. Just damage everywhere."
Mount Clear newsagent Shane Stevens says a sign blew off and lifted the roof, sending water into the post office.
"It's lifted the roof so the back of my post office is a lake," he said.
"I walked in in the dark because there was no power ... there was water everywhere.
"Then [I] turned the lights on and I then could see what had really happened."
© ABC 2012
01:01 EDT A two-year-old boy has died and a girl suffered serious injuries after a tree fell on their house at The Patch in the Dandenong Ranges, east of Melbourne, as severe thunderstorms swept through Victoria on Saturday evening.