?Unexpected? floods in Queensland leave 15 missing as ex-cyclone Seth wreaks havoc

Parts of Queensland are experiencing major flooding, with the aftermath of ex-tropical Cyclone Seth causing "unexpected" prolonged heavy rain and storms.

The Bureau of Meteorology said there was major flooding in the Wide Bay and Burnett regions, north of Brisbane, causing highways to close and cutting off some towns.

Marodian near Gympie received more than 670mm in the 24 hours to 9am with many other areas receiving at least 300mm.

The Bruce Highway reopened late Saturday morning after the downpour forced it to close earlier.

There were warnings for more heavy rain on Saturday and authorities issued an emergency alert for Maryborough, urging people to reconsider travel.

Queensland Police confirmed one person had drowned after his vehicle became submerged in flood waters at Kanigan, Wide Bay on Friday night.

Police and emergency services responded to reports of a ute being swept off the road on Cherry Tree Road near the Bruce Highway about 7.30pm.