(CNN) -- Authorities were using military helicopters and a C-130 cargo plane Sunday to evacuate thousands of residents stranded by rising floodwaters in the eastern Australian state of Queensland, the government said.
Heavy rains in recent weeks have swollen rivers beyond their banks, threatening a number of communities in Queensland and New South Wales.
Authorities were using the plane and helicopters to evacuate patients from a hospital in particularly hard-hit Queensland town of St. George, where officials were warning about 4,000 residents to get out of the path of what officials say will be a record-breaking flood.
"This is a very serious situation and I urge people to cooperate,'' Queensland Premier Anna Bligh told CNN affiliate Nine Network.
The Balonne River is expected to crest Monday at 15 meters (49.2 feet), swamping the town of St. George.
Prime Minister Julia Gillard said authorities were coordinating calls for assistance.
""Emergency Management Australia has liaison officers in flood-affected regions to ensure that requests for any further assistance can be actioned immediately," Gillard said in a statement.
Food and medical supplies have been flown to isolated communities elsewhere in Queensland, authorities said.
Rescue workers on Sunday recovered the body of a woman who died trying to drive her pickup through floodwaters, authorities said.
Jane Sheahan was swept away Friday in the Queensland town of Roma, authorities said.
Witnesses told CNN affiliate Nine Network that Sheahan managed to hand off her 7-year-old son, Darcy, to a would-be rescuer before she was swept away.
In the neighboring province of New South Wales, thousands of people remained isolated despite reports of receding floodwaters in some areas.
Emergency officials lifted a number of evacuations ordered evacuations early Sunday, though they warned residents not to walk, drive or swim in the receding waters.
Flood waters have started to recede around North Moree after five days of major flooding, the New South Wales Emergency Services said, but many of the town's streets remain closed.
Aerial assessments show some 300 homes and businesses have been inundated -- making it the worst flooding in nearly 60 years, CNN affiliate Seven Network reported.
Major flooding has also affected communities along the Namoi River, where the town of Wee Waa has been cut off, the New South Wales Emergency Services said. Major flooding is expected to continue there until the middle of this week.
Other communities affected by the Namoi River include Boggoabri, Narrabri Bugilbone and Goangra, with flood waters closing roads and inundating some rural properties.