Dead Qld toddlers 'signs of heat exposure'

Two toddlers found dead in a car south of Brisbane showed signs of exposure to extreme heat, Queensland police say.

Paramedics tried to revive the children, aged one and two, after being called to a home in Waterford West about 1.35pm on Saturday.

Police said they were interviewing the girls' parents and had taped off the house where forensic officers were working to confirm the cause of their deaths.

"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."

Police have declared a crime scene around a black station wagon parked in the driveway at the front of the property on Logan Reserve Road.

Police said the investigation was in its early stages and were trying to piece together how long the girls were in the car and how they came to be there.

"As a normal course we are speaking with the parents," Detective Inspector White said.

"We'll be speaking to quite a number of people. Because the purpose of this is to find out what has taken place."

Qld Police was mindful of the impact on its officers and other emergency services who respond to such tragic and disturbing incidents.

"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."