A father charged with the manslaughter of his toddler twin girls had been drinking before he left them in a hot car, police said.
Witnesses heard screams and saw 24-year-old Asa North running as he carried the girls from the car park in front of their home in Carrollton, near Atlanta, Georgia, to an inflatable pool. Neighbours joined him, frantically trying to revive the girls with water and ice packs.
But they were already unresponsive, and were declared dead at a nearby hospital a short time later.
Outside temperatures were in the 90s on Thursday before police were called at 6:34pm.
Investigators were trying to determine how long the girls remained in the parked car.
"We do believe alcohol is involved," said Carrollton police Captain Chris Dobbs, who identified the girls as Ariel North and Alaynah North. "We do believe the father, sometime throughout the day, had been consuming alcoholic beverages."
North is charged with two counts of involuntary manslaughter and two counts of reckless conduct, Carroll County jail records show. Police were awaiting the results of blood tests to determine his alcohol level.
The girl's mother was at Grady Memorial Hospital in Atlanta at the time, visiting her sister, who had been in a serious car crash on Wednesday, Capt Dobbs said.
"I guess he forgot about the kids and left them in the car," said Donnie Holland, the twins' uncle. "He should have took care of them better than what he did. He should have never been in the house asleep. He should have got the kids out of the car the time he got out of the car."
It was not clear who discovered the girls in the back of the car.
"The neighbours heard some screaming - I guess coming from the father - and saw him running around back with the two children," Capt Dobbs said. "One of the neighbours got some ice packs out of the freezer and carried it out there."
Arriving officers performed CPR, but the girls could not be revived. Post mortem examinations were being carried out at the Georgia Bureau of Investigation crime lab.
The girls are the 25th and 26th children to die this year in hot vehicles in the US, more than double the number by this point last summer, said Janette Fennell, president and founder of KidsAndCars.org. By this date in 2015, 12 children had died in hot cars, Ms Fennell said.