A set of twins who vanished over the weekend only to be found unresponsive inside a pickup truck parked outside their Louisiana home have been declared dead.
Oliver and Aria Orr were found in the vehicle outside their Bossier, Louisiana, home at about 3 p.m. Saturday, authorities said.
By Sunday, the Shreveport Times reported that the 3-year-old brother and sister had died.
The twins were discovered after neighbors said their mother asked for help locating the children.
After they were found unresponsive in the white pickup, police and fire officials rushed the twins to the hospital.
Police told InsideEdition.com the deaths were determined to have been heat related. The temperature in the area reached 90 the day of the twins' deaths.
However, investigators said it was unclear if the children had been placed in the car or if they got inside on their own.
The children showed no physical signs of trauma.
In the wake of their deaths, an outpouring of supportive messages were posted on a Facebook page that appears to belong to the twins' father, Travis Orr.
"I have no words other than we are all praying for your family. We love you and are here if and when you need us," wrote one poster.
Another wrote: "My heart breaks for all of you. I can['t] tell you how sorry I am Travis."
A call made to a number matching Orr's name and address rang unanswered Monday.
Also on Orr's page are updates following an apparent accident that left Oliver in the hospital in a neck brace just weeks before his death.
Bossier City police spokesman Mark Natale told KTBS-TV that it remains unclear how the children got inside the truck.
“We don’t know if the children climbed in the car or if they were left in the car,” he said.