A five-year-old girl saved her younger brother’s life in a Christmas Day car crash that killed their parents and left them alone for more than two days.

Jake Day, 28, and Cindy Braddock, 25, died after their 4WD left the road and rolled about 10km from their hometown of Kondinin, 280km east of Perth.

The couple had driven from Northam, 200km away, about 1am on Sunday and the crash left the family’s Landrover on its roof in bushland.

Their three children, who survived the accident but were trapped in the upturned car with their dead parents, weren’t found until about midday on Tuesday.

Mr Day’s cousin Michael Read told reporters the couple’s daughter had saved her younger brother’s life during their two-and-half-day ordeal.

“The five-year-old became unstuck in the vehicle and she then got the one-year-old out of the car seat when they were stuck in the car for the 55 hours in 30C heat,” he said on Wednesday.

“If it wasn’t for the five-year-old undoing the buckle on the one-year-old’s seat he wouldn’t be with us today.”

He said family friends discovered the accident site, where the couple’s daughter and two sons, aged one and two, were badly dehydrated inside the station wagon, with the older boy still strapped to a seat.

They were flown to Perth Children’s Hospital for medical treatment and all are in a stable condition.

“It would have been hard for the three children to be in that car for the whole time,” Mr Read said.

“Nobody knows what they went through.”

Shire councillor and local hotel manager Darren Pool says residents remain in shock over the “traumatic” incident on the town’s outskirts.

“Being so close to town and no one had noticed it,” he said.

“People have been driving past it for a couple of days. That’s probably the biggest shock for me.”

Mr Pool said Mr Day and Ms Braddock were “battlers” who “did everything for their kids”.

“What we do from here is going to be the hard bit,” he said.

Casey Guyer and Kailee Wallace have set up a Go Fund Me page to help the couple’s family, with more than $6000 raised of the $10,000 goal.

“Devastatingly Jake and Cindy did not survive the accident but an angel was looking over the kids,” they wrote.

“It was a miracle their beautiful babies survived for over two days in the Australian outback.”