Effingham, IL – Authorities say preliminary results indicate carbon monoxide poisoning caused the death of a St. Elmo man Sunday afternoon.

22-year-old Johnathon Warner was found unresponsive in a vehicle outside of The Hangout Nightclub about 2:45pm Sunday.He was pronounced dead at the scene at 3:22pm.

Preliminary results from Warner’s autopsy Monday indicated he likely died accidentally due to carbon monoxide poisoning.The final autopsy report and toxicology tests are still pending.

As winter approaches, Effingham County Coroner Duane Guffey reminds motorists to be careful when stranded in a vehicle, or using an idling vehicle to warm up or take a nap.Guffey said a defective exhaust system can release carbon monoxide into the passenger area of a vehicle.