PM reaches out to families of the missing

The prime minister says nature has flung its worst at Australians over the past week following Cyclone Debbie.

Malcolm Turnbull has reached out to the families of people who went missing during the flood crisis. (AAP)

Prime Minister Malcolm Turnbull has reached out to the families of people who went missing during the east coast flood crisis.

"The thoughts and prayers of all Australians are with the families," he told reporters in Canberra.

Police divers in NSW are on Tuesday searching for a mother and her two children feared drown in a car in a river in the state's north.

Another child, the woman's eight-year-old daughter, managed to escape the car as it slide into the swollen waters of the Tweed River at Tumbulgum on Monday afternoon.

In Queensland, where Debbie unleashed last week, the missing are: a 65-year-old man who was walking in Lamington National Park, a 50-year-old David Heidemann from Mondure man and 58-year-old John Frost from Mount Pleasant in Mackay.

"We share the anxiety and concern of those who have loved ones that are missing in the floods," Mr Turnbull said.