Police have assisted with the urgent evacuation of the Maryborough CBD in Queensland after a temporary flood levee gave way.
The sudden alert followed a wild few days of widespread flooding in the Wide Bay-Burnett region and a tropical cyclone warning being issued for the coast of Far North Queensland.
A text issued by the Fraser Coast Regional Council on Sunday urged residents in Maryborough's CBD precinct to urgently move to higher ground after water behind the levy backed up behind the level of the flood barrier.
"The underground valve on the dry side of the levy has been damaged resulting in immediate flooding in the Maryborough CBD," the text reads.
Queensland Police issued an emergency declaration under the Public Safety Preservation Act for Maryborough premises due to the ongoing flooding, with officers assisting evacuation efforts.
Fraser Coast Council said that all properties in the CBD had been evacuated by 2pm.
The exclusion zone includes parts of Adelaide St, Kent St, Lennox St, Alice St and Richmond St.
"Businesses and residents within the exclusion area have been door knocked and advised to leave for higher ground as soon as possible," a QPS spokesman said.
Earlier, Queensland Premier Annastacia Palaszczuk said flooding in the city of Maryborough was expected to peak in the evening and reach 10.5m.
About 80 homes were expected to be impacted.
A tropical cyclone warning has also been issued for a deepening tropical low off the coast of Far North Queensland, with the weather bureau forecasting gale-force winds, heavy rain and unusually high tides.
The tropical low is located about 275km northeast of Cooktown in the Coral Sea.
The Bureau of Meteorology said the system may intensify to tropical cyclone strength and if one develops, it would be named Tiffany.
The system is tracking southeast in the northern Coral Sea and was forecast to cross the Cape York Peninsula on Monday, before moving into the Gulf of Carpentaria.
Senior Meteorologist Dean Narramore said the bureau was closely monitoring the system.
"We are expecting heavy rainfall and damaging winds as a result of this system, so regardless of whether it is a tropical low or a tropical cyclone, there is still an increased risk of flooding and some localised damage in the region," Narramore said.
"Tropical systems can intensify very quickly, and shift direction, so we will be updating our warnings and advice to the community and our emergency services colleagues as this system progresses."
The current warning zone extends from Cape Grenville to Cape Tribulation, including Lockhart River and Cooktown, with people living in these areas advised to take precautions and listen out for the next advice at 2pm.
Residents in Kowanyama to Mapoon including Weipa are in the watch area, and should consider what action they will need to take if the cyclone threat increases.
The warning comes after some areas of the Wide Bay-Burnett region were hit by 673mm of rain before Saturday morning, leaving devastating consequences.
Highways were washed away and one man died during the deluge.
A teenage girl who disappeared in floodwaters at Booubyjan remains missing, with authorities desperately searching for her.
Narramore said the ex-tropical cyclone's remnants combined with very moist and humid air to create a "blob" of heavy rainfall that remained stationary over the region.
Queensland emergency services have urged residents to stay at home, warning that "even if you live in the area this is likely not like any weather you would have seen in your lifetime".
"We expect weather conditions to ease now, but that unexpected rain that fell in the catchment area over 24 hours was unprecedented," Palaszczuk said.
The body of a 22-year-old Sunshine Coast man was discovered in a ute on Saturday morning after it was swept off Cherry Tree Rd at Kanigan near the Bruce Highway on Friday evening.
Police said on Saturday afternoon a man had been found hanging on to a tree in floodwaters near Gympie and his teenage companion was missing.
The pair became trapped near the Burnett Highway and Murgon Gayndah Rds at Booubyjan in the early hours of the day.
"It is believed the pair were in a Toyota Camry sedan and managed to get out of the vehicle before it was swept away," police said in a statement.
"Shortly before 12.30pm, a 40-year-old man was rescued after being located clinging to a tree and taken to Bundaberg Hospital for treatment."