CINCINNATI — Authorities pledged on Thursday to find out what went wrong in the death of a 16-year-old boy they say became trapped by a minivan bench seat in a school parking lot and whose body was found about six hours after he first called 911.

Police Chief Eliot Isaac said something went "terribly wrong" in Kyle Plush's death. He said a dispatcher was put on administrative leave and the actions of all personnel involved will be reviewed.

Hamilton County prosecutor Joe Deters said his office is trying to identify experts to help its own probe with the coroner's office. The coroner ruled the teenager died of asphyxia, from his chest being compressed.

A telephone message was left for the boy's parents on Thursday.

Isaac called the boy's death "a horrific tragedy."

"We share in their heartbreak," he said.

Plush first called 911 at about 3:15 p.m. Tuesday, saying he was stuck inside a van in "desperate need of help." But he was unable to hear the dispatcher's questions, police said, and a callback to his cellphone after it disconnected went to voicemail. Responding police drove through the area looking for signs of anyone in distress but saw nothing out of the ordinary in the school complex, which has several parking areas.