SAN ANTONIO — A five-year-boy died on Wednesday after being left in a hot car all day after his mother thought she had dropped him off at school before leaving to work, police say.

San Antonio Police Chief McManus said in a media briefing, the boy’s mother went to work in the morning and typically drops the child off at the Pinnacle school before driving to her place of work, next door.

The mother then left work this afternoon to go pick up her child from the school and was told the child never arrived. She told police she thought that she had dropped the child off before going to work. The child was discovered deceased in the backseat of the car, still in his car seat.

Detectives are investigating including determining whether it was accidental or criminal, Chief McManus said.

We’ll update this article as new information becomes available.