Authorities in San Antonio are investigating the apparent hot car deaths of a 3-year-old girl and her 6-year-old brother after the local sheriff said there were “inconsistencies with the story” told by the children’s mom.

The mother, Tiona Islar, allegedly told authorities she last saw her son and daughter in the home around 10 a.m. Saturday, Bexar County Sheriff Javier Salazar said. Islar said she fell asleep, and then around 3 p.m. she found the children in the car and took them inside, Salazar said. Authorities were called around 3:25 p.m., the sheriff said.

A responding deputy “was simultaneously trying to perform CPR on both children, but unfortunately was not successful,” Salazar said. The siblings were pronounced dead at the scene, Salazar said.

Islar, 28, has been arrested on charges of injury to a child, according to the sheriff’s office.

Islar was “mostly cooperative” when taken in for questioning on Saturday, the sheriff told reporters, but he added the circumstances surroundings the deaths were not clear.

Tiona Islar has been arrested on charges of injury to a child.
Bexar County Sheriff’s Office

“The initial report was for, that the children were left in a car,” the sheriff said on Saturday. “However … there just are some inconsistencies with the story that we’re being given.”

“Something’s not adding up with this case,” Salazar said.

A sheriff’s office spokesperson said on Monday that authorities are still investigating and they’re awaiting the cause and manner of death from the medical examiner.

At least 29 children have died in hot cars in the U.S. this year, according to national nonprofit KidsAndCars.org. At least 1,159 children have died in hot cars since 1990.

Salazar warned, “Every second counts when you’re talking about a child in a hot car.”

“If you come upon a child locked in a car, make every intent to open the doors initially,” he told reporters. “If they’re locked, at that point, it’s safe to say, break a window, do whatever you have to do to get that kid out of there.”