Emergency services in Queensland are searching for a 14-year-old girl swept away in floodwaters near Gympie early Saturday morning.
Areas of the Wide Bay and Burnett, Fraser Coast and Gympie region have been inundated with up to 650 millimetres rain after ex-Cyclone Seth crossed the coast on Friday morning.
An emergency alert for Goomeri, Kilkivan and Woolooga was issued on Saturday afternoon, warning of "significant flooding" and urging residents of those areas to stay in their homes.
Police were called to reports of a man and teenage girl caught near the Burnett Highway and Murgon Gayndah Road at Booubyjan. The pair escaped their vehicle before it was swept away.
Just after midday, a 40-year-old man was rescued after being located clinging to a tree and was taken to Bundaberg Hospital. Rescue crews are continuing to search for the girl.
Earlier Saturday, police found a 22-year-old Sunshine Coast man dead inside his car which became submerged in floodwaters at Kanigan on Friday night.
They were only able to retrieve the man's body when flood conditions allowed swiftwater crews to reach the vehicle.
Residents of Maryborough have been issued an emergency alert for major flooding in the Mary River that is expected to exceed nine metres on Sunday morning as rain continues to fall.
Construction of a CBD flood barrier was underway, while an evacuation respite centre opened at the city's Brolga Theatre and Convention Centre.
The weather event dumped up to 650 millimetres of rain in 24 hours in some areas, pushing river heights up to 16.75 metres.
Bureau of Meteorology forecaster Laura Boekel said most of the rain was "very localised" between Gympie and Tiaro, describing the intensity of the falls as "incredibly rare".
"We very rarely see thunderstorms staying in the location for such a long period of time," she said.
"They saw 600-plus millimetres in 12 hours so a really extraordinary amount of rainfall in a short period of time.
"So while we were aware that we were expecting thunderstorm activity and we could see heavy rain associated with that, the magnitude of what we saw really escalated throughout the night.
"Gympie didn't see that really intense rainfall, it's actually upstream from that intense rainfall."
Areas without power are likely to remain cut off as crews are not yet able to attend sites in need of repair.
At a flood emergency media briefing on Saturday, Premier Annastacia Palaszczuk said 649mm fell at Mt Kanigan, 506mm at Glenwood and 342mm at Kilkivan.
"This is a lot of rainfall in such a short period of time," she said.
Meanwhile, four people were rescued from floodwaters in the town of Woolooga and flown to Bundaberg Hospital.
Longtime Woolooga local Brian Dray said the creek that ran through his property was in flood.
"It's going down now, but about six o'clock this morning it was the highest I've ever seen it," he said.
The towns of Tiaro and Miva were put on emergency flood alert and the Bruce Highway was cut by floodwaters but has since reopened.
Police Deputy Commissioner Steve Gollschewski warned the highway could be closed again with rain still falling.
"There has been significant damage to some of the roads. Before anyone travels, [ask if] they absolutely have to, that's the first thing: don't go out in that area unless you absolutely have to," he said.
Flooding was minor in Bundaberg, although the city and surrounds received more than 200mm.
Maryborough to be inundated
Fraser Coast Mayor George Seymour told ABC Radio Brisbane that central Maryborough would be inundated on Sunday.
"We are looking at a potential major flood of the Maryborough CBD ? so we are right now following all the procedures to close down bridges and get the flood barrier system up in the CBD," he said.
"We have a number of communities that will most likely get cut off like Granville, the bridge over into the larger Maryborough area, as well as other areas ? Tiaro right now is going through a major flood.
"But other areas like Tinnanbar, Poona, there's a whole series of communities in the west that will be cut off for a period of perhaps a day or three."
Mr Seymour urged residents to be prepared for the flood and to limit travel.
"[I advise them] to make sure they have enough food and what they need for the next three days."
There have been more than 75 calls for help across the state with multiple swiftwater rescues.
Earlier on Saturday, meteorologist Helen Reid said it was "amazing what an ex-tropical cyclone can do once it's made landfall".
"But over the course of the night, the dynamics of what was happening really intensified and we saw all that rainfall.
"We can point the finger straight at ex-Tropical Cyclone Seth and it will be a name that a lot of people won't want to use for their children."
© ABC 2022
00:46 AEDT Severe thunderstorms are expected to lash eastern parts of the state today as Victoria continues to count the cost after days of wild weather.