Police fear for safety of two people missing in rising waters, while hundreds of people are evacuated in Devonport, Launceston, Wynyard and Deloraine

Northern Tasmania is grappling with the most devastating flooding it has experienced in decades after a severe weather system that devastated Queensland and New South Wales hit the state on Monday.

As night fell, police held grave concerns for two elderly people reported missing in the Tasmanian floodwaters, which continue to rise.

By Monday night more than 100 people in Latrobe in Tasmania had been evacuated by helicopter and boat, including a family of three rescued from the roof of their car. Residents in St Leonards, in Launceston, had also been evacuated.

Evacuation centres have been established in Devonport, Launceston, Wynyard and Deloraine, with 3,500 homes without power and significant livestock losses at dairy farms along the Mersey river.

One 81-year-old farmer near the river was swept away by flood waters as he went to check on his livestock, and was reported missing by his wife on Monday afternoon. Police are still searching for him, along with one other elderly person also missing.

Tasmania braces itself for floods and extensive damage – rolling report Read more

The mayor of Latrobe council, Peter Freshney, said the area, in the state’s north, had already experienced major infrastructure damage by Monday afternoon. Livestock had also been lost, he said, and 3,200 homes had been left without power.

“People will have property damage to their houses and the like, we understand there’s been significant stock loss, hundreds of cattle have been lost on particular farms upstream,” he told the ABC.

“We’ve seen a number of dead cattle and the like being washed downstream so it’s going to impact right across our municipality and in the wider region in terms of personal properties farms and industry, our local community, it will have a huge impact that there’ll be huge cost.

“But we’re really focusing on the people and rescuing them and a lot of work done to ensure that we can help them as best we can in the recovery process.”

A flood watch is in place for all Tasmanian river basins, with some areas experiencing in excess of 200mm of rainfall.

Tasmania’s police minister, Rene Hidding, urged people to stay away from the water. “Can I call on all Tasmanians to be absolutely responsible in the coming days,” he said.

“There is no circumstances where anybody should risk their lives. Don’t try to take nature on – it leads to tragedy. We already have grave fears for two of our fellow citizens and we pray for them. There is simply no case to enter flood waters with a motor vehicle or in person.”

The state hasn’t seen such flooding since 1929, when flooding in Launceston left several people dead.

Earlier in the day, three people were confirmed dead in the aftermath of the storm, two in NSW and one in the Australian Capital Territory. NSW was left reeling from comprehensive damage to beaches, surf clubs and homes after king tides and 13-metre waves during a weekend of storms.

The body of a 37-year-old man was recovered from the Cotter river in the ACT on Monday morning. Police said the man had been found stuck and unable to cross the river in his four-wheel drive about 4.30pm on Sunday. As rescue crews were trying to reach him, his car was swept away by the flood waters, flipped and disappeared from view.

About 5pm on Sunday, emergency services were called to Leppington in NSW after receiving information that a vehicle was being washed away on a causeway. The search resumed at 6.30am on Monday. Police found the body of a man in a vehicle.

South-east Australia on flood alert as east coast low leaves Sydney Read more

In Bowral, also in NSW, emergency services were called to Mittagong creek at 5.30pm on Sunday after reports a car was trapped in flood waters. Police were unable to locate the vehicle until 8.30am on Monday. The body of a 65-year-old man was found inside.

As Sydney’s eastern beaches continued to be hit by dangerously strong waves and high tides into Monday evening, the Coogee surf club was deemed as at risk of collapse, with emergency crews working to stabilise the building. NSW police also expressed their frustration at people continuing to swim at beaches and drive through flood waters, with a search under way for a person who slipped off the rocks at Bondi and into the dangerous surf.

The acting assistant commissioner of NSW police, Kyle Stewart, said the flood waters were “deadly”. “We can’t put it any other way,” he said.

“What do we have to say to get the message across? Emergency service personnel this morning have had the devastating task of retrieving the bodies of two men.”