Four children are part of a group of seven people missing in a remote part of southern Western Australia experiencing flash flooding and heavy rainfall.
Police say two elderly male drivers, four children aged between 12 and 17 years and an elderly woman left Kalgoorlie Boulder on Sunday and were driving about 650km north east towards Tjuntjuntjarra.
Western Australia Police Inspector Mick Kelly said he holds urgent welfare concerns for the group, believed to be family members, as they were meant to arrive at their destination on Monday morning.
He has been told the cars have minimal food onboard but one has water, bedding and camping gear.
"We're praying that they've stayed with the car," Inspector Kelly told reporters on Tuesday afternoon.
He said the search effort has been hampered by the conditions, as a plane looking for the group was only able to stay in the sky for about an hour on Tuesday.
"There's 120 millimetres forecast to hit our area in the next 24 hours and we've also got tropical weather forming at the north coast," Inspector Kelly said.
"But our pilots are the experts and quite simply, while we want to have every opportunity to bring these people back to the community safely, we can't afford obviously to put those that are out there looking and searching in danger."
The group is reported to be travelling in a beige Toyota Landcruiser, registration number A683 and a white Mitsubishi Triton, registration number KBC8881.
The Bureau of Meteorology has issued a severe weather warning for parts of the Goldfields, Eucla and South Interior districts because of heavy rainfall and flash flooding.
"Locally intense rainfall which may lead to dangerous and life-threatening flash flooding is also possible," the alert stated.
Anyone with information about the group's whereabouts has been asked to contact Kalgoorlie Police Station.