Australian authorities declared a state of emergency in Queensland Wednesday as torrential rain and gale force winds caused extensive flooding and left one man dead.

Almost 30,000 homes were without power in the state's southeast, where some areas recorded 300 millimetres (12 inches) of rain in 24 hours and wind gusts exceeding 100 kilometres (62 miles) an hour.

Ambulance officers said a 46-year-old man was killed by flying glass when a freak wind gust smashed in a window on a building on the Gold Coast tourist strip.

Queensland Premier Anna Bligh declared a state of emergency including the Sunshine Coast and the Gold Coast and extending inland to Toowoomba.

Prime Minister Kevin Rudd said the federal government was ready to offer assistance if required.

Rudd said he had received a briefing on the emergency and was told the floods were causing havoc on roads in southeast Queensland.

"There are quite a large number of people who are at this stage isolated in their vehicles and I am further advised there are a number of schools that have been cut off as well," he said.

Police said tables, chairs and barbecues had been blown off the top of high-rise buildings on the Gold Coast and warned people to take extreme care if they ventured outside.

School pupils in the town of Brookfield were stranded in their classrooms unable to get home because of the rising waters.

"The parents are talking to the teachers on their mobiles and they've been assured all the kids are safe," a spokeswoman for local politician Bruce Flegg said.

Meteorologists have warned the wild weather could last for days.