Queensland authorities have said the state’s north was entering “unprecedented territory” as monsoon rains battered the city of Townsville, setting record flood levels and destroying homes.

As the natural disaster entered its four day, the state emergency service confirmed on Saturday that 80 people had been rescued. It was too early to quantify the damage to homes, although some media reports said at least 50 homes had been affected so far.

“We have not been in this scenario before,” said the premier, Annastacia Palaszczuk. “There has been a lot of rain that has been falling, especially over the Townsville catchment, and some of these levels are unprecedented.

“It is very important that you listen to the local authorities today.”

The worst of the conditions were expected over the next two days, and authorities described the next 48 hours as “crucial”. On Friday, Palaszczuk had described the incoming monsoon as a “once in a 100-year” event and Townsville was declared a disaster zone.

SES volunteers are seen rescuing residents in Rosslea, Townsville Photograph: Andrew Rankin/AAP

Authorities said it was crucial that residents listened to emergency measures, did not drive through floodwaters and paid urged heed to warnings about moving to higher ground.

“From Mackay north and west, there is going to be flooding so for the broader community, please, if it’s flooded, just forget it,” the state’s disaster coordinator, Bob Gee, said on Saturday.

Between 100mm and 300mm of rain was expected within the next 24 hours and the town’s seven-day rainfall record was also likely to be toppled.

“Townsville is currently seeing a record flood height of the Ackland Weir,” Gee said. “Earlier this morning it was a height of 2.36m but we can expect that, with forecast rainfall, to reach up to 2.9m over the weekend at some stage.”

A Bureau of Meteorology spokesman said the areas at risk over the next few days included Herbert and Lower Burdekin.

“We expect the peak in the rainfall to recur again tonight and continuing into next week,” he said. “There’s several more days to go in this flood event.”

An emergency alert flood message was in place for residents in areas adjacent to the Bohle River, Saunders Creek and Stoney Creek, and for the suburbs of Deeragun, Jensen and Burdell.

Schools and businesses in Townsville were to remain shut and thousands of residents had been evacuated to higher ground, AAP reported.

Homes and businesses have been destroyed as flash floods washed through streets, sweeping away cars, equipment and livestock.

Just another fun day in #Townsville . It never rains here; it #floods . Being in a QLDer on 4M steel stumps has its benefits. The Mazdarati is safe at Dad's above the 1946 floodline and we have the Rover! Only leaving if the power cuts. #TownsvilleFloods2019 pic.twitter.com/KLQZJjrsmB — madvoice (@madvoice) February 1, 2019

Landslips destabilised an apartment complex, blocked roads and caused homes to be evacuated. As of Saturday morning, 100 homes were at risk from the bulging Ross River dam, which was at 185% of capacity late on Friday.

Soldiers were mobilised to help sand-bag vulnerable properties as authorities went door to door telling people they should leave at-risk homes.

The worsening flood conditions in north Queensland come as fire services in Tasmania battle blazes that have destroyed wilderness areas in the pristine island state. Palaszczuk acknowledged that the heavy rainfall had been better news for drought-affected parts of Queensland, west of Townsville.

Flood warnings remained in place for the following catchments: Mulgrave, Russell, Tully, Murray, Herbert, Ross, Bohle, Haughton, Burdekin, Don, Isaac, Leichhardt, Nicholson, Gregory, Flinders, Cloncurry and Diamantina Rivers.

Further north, coastal communities on the Gulf of Carpentaria had been told to prepare for the highest tides of the year as the monsoon trough whipped up gale force winds.