An 18-month-old boy was found dead Wednesday inside a van at his home in northeastern Kentucky, authorities said.

Fleming County Deputy Coroner Gary Workman said he suspected the death was heat-related, but said an official cause of death wouldn't be made until after an autopsy planned for Thursday.

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Workman said the boy and his 2-year-old sister were found in the van by their mother Wednesday morning at their home at Grange City, about 60 miles northeast of Lexington. The van doors were locked and the mother had to break a window to get to her children, he said.

The girl was taken to Fleming County Hospital in Flemingsburg, where she was alert and "appeared to be in good shape," Workman said.