Police will investigate how long two little girls were sweltering inside a hot car in Queensland before they were pulled out on Saturday.

A 27-year-old woman, reported to be their mother, has been charged with double murder for the distressing deaths of the toddlers, aged one and two, who police said seemed to have been exposed to “extreme heat”.

A crime scene has been taped off around a black station wagon parked in the front of the suburban Logan property, south of Brisbane.

One neighbour has claimed the children were spotted inside the vehicle up to seven hours before emergency services arrived at about 1.35pm, when temperatures had reached 31 degrees outside.

Paramedics tried unsuccessfully to revive the young sisters after being called to the home at Waterford West.

“They were both declared deceased at the scene,” Detective Inspector Mark White said.

“The two children exhibited signs of being exposed to extreme heat and that is forming the direction of our investigation.

“We are speaking the parents of those children. It’s a very tragic incident which has occurred.”

Two young girls have died after being found unresponsive in a hot car parked outside a home in Logan. @EmilyPrain9 #9News pic.twitter.com/9PlLSGLgEs

— 9News Queensland (@9NewsQueensland) November 23, 2019

Neighbours described confronting scenes as the children’s lifeless bodies were carried by police.

Temperatures inside sealed vehicles can be as much as 40 degrees hotter than outside, with most of the temperature increase happening rapidly in the first five minutes.

In those conditions, children can very quickly become distressed, dehydrated and die from organ failure.

Police are attempting to establish how long the girls had been in the station wagon.

The Courier Mail reports that one woman claims her grandson saw the girls in the car as early as 6.30am – seven hours before emergency services raced to the property.

The family reportedly moved in as recently as six months ago.

Police interviewed the children’s parents for several hours before confirming on Saturday night that a woman known to the tiny victims had been charged with two counts of murder.

She was taken into custody and is expected to appear in Brisbane Magistrates Court on Monday.

As news of the tragedy spread around the suburb, shocked neighbours arrived to lay flowers and pay tribute to the little girls.

“Absolutely heartbreaking,” wrote Jen May on Facebook. “RIP little darlings.”

Support is being offered to officers who attended the confronting scene, which police described as “tragic”.

“We are putting a lot of emphasis on supporting our people,” Detective Inspector White said.

“One of our priorities in addition to conducting the investigation is the wellbeing of our staff and our other emergency service colleagues.”

The Logan property was also searched in 2016 – before the family moved in – in relation to the murder of Beenleigh schoolgirl Tiahleigh Palmer.

-with AAP