WASHINGTON, Illinois — A 36-year-old Kingsford man died Wednesday of compressional asphyxia after being trapped under an electrical control box at Caterpillar’s Peoria Proving Ground in Illinois’ Tazewell County, according to a coroner’s report.

Justin Perry, a contractor at the facility, was pronounced dead at the site at 11:15 p.m. Wednesday by Coroner Charles R. Hanley. Authorities were notified at 8:52 p.m. of an incident at the proving ground, the Peoria Journal Star reported.

The case remains under investigation by the Occupational Safety and Health Administration, the Tazewell County Sheriff’s Office, and the Tazewell County Coroner’s Office, the newspaper said.

Caterpillar said in a statement it was “deeply saddened” by Perry’s death and would work with authorities during the investigation.

The Peoria Proving Ground, according to the Chicago Tribune, is a secluded 2,500-acre site where the manufacturer develops and tests heavy equipment.