Witnesses who saw two tornadoes that tore through communities in north-eastern Victoria say it was like a bomb went off.
At least , two in a critical condition, after the tornadoes touched down in a line stretching from Cobram to Rutherglen just after 7:00pm (AEDT) yesterday.
Authorities say it will take days to clean up the damage.
Buildings in the historic town of Rutherglen were severely damaged, with awnings ripped off and windows smashed.
Trees were shredded and torn out of the ground by their roots.
One witness described how another tornado ripped fence posts out of concrete bases at Tamleugh North, about 112 kilometres south-east of Rutherglen.
There are also reports of widespread damage at Tatong and Swanpool, near Benalla.
At Mulwala, the Denison County Caravan Park was badly damaged, with roofs torn off and trees scattered amongst vans and cabins.
Daryl Davey, the deputy mayor of the Corowa Shire, which includes Mulwala, says it was like a war zone.
"We were hanging on to the windows at home," he told ABC local radio.
"There was debris flying through the air, aluminium annexes, fences, barbecues, you name it. Everything was in the air at one stage."
He says he has never seen anything like this before.
"It's just like a bomb went off," he said.
"The trees have got no leaves down the road a bit. It's just defoliated them. It looks like Agent Orange has sort of gone through there and stripped them.
"There's corrugated iron wrapped around power lines, trees. Trees are all uprooted and laying on the ground and it's just a mess."
About 18 kilometres away at Bundalong, on Lake Mulwala, Liz Menhenett said it the hailstones were huge.
"My husband called me outside and it sounded like a plane crashing," she said.
"All of a sudden we had the huge hailstones and then after that just the wind blew and the trees were coming down everywhere."
Bundalong Holiday Resort owner Michael Bourke says the ferocity of the storm took him by surprise.
"Last night you couldn't see the country for the trees," he said.
"Now you're looking at trees everywhere, in the swimming pool. It's just unbelievable."
Another resident, Caroline O'Dwyer, says the hail was coming down in sheets and that was followed by a huge roar.
"It came through, you could just hear it coming. Everything was shaking, the windows were shaking," she said.
"We moved the kids into the passageway because it was just like everything was going to explode."
She says they were lucky.
"Our house is intact and we're all safe that's the main thing," she said.
"It's a bit of a shock to walk out and see the mess though in the daylight."
© ABC 2013
23:36 EST New South Wales authorities say they are dealing with the largest storm operation in a decade after three people were killed in "cyclonic" conditions that have battered parts of the state for hours.