Haldimand OPP say a man was transported to the trauma centre on Sunday following an incident in the village of York.
They were called out in the morning to investigate a report of shots being fired in the vicinity.
That afternoon, a 56-year-old individual was taken into custody and subsequently airlifted to a trauma centre by air ambulance with serious, non-life-threatening injuries due to the detonation of live ammunition in a fire.
There was no indication of a firearm being involved in the incident.