Two children in Texas have died after they were locked in a hot car Friday as temperatures soared to 96 degrees, according to police.

A 16-month-old boy and a 2-year-old girl were killed, police said. Their identities were not released.

Deputies from the Parker County Sheriff's Office were called to a home west of Lake Weatherford shortly after 4 p.m., police said.

The children's mother told police that they "took off." After searching for them on the property, she found them inside a small four-door vehicle, where they had somehow locked themselves inside, police said.

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The mother then broke one of the windows and found the children unresponsive, police said. They were pronounced dead at 4:33 p.m.

In a statement, Parker County Sheriff Larry Fowler called the case especially heartbreaking and said that it is still in the early stages of the investigation.

No further details were immediately available.