A 57-year-old man suffered critical injuries while out on his mountain bike at Milton's Kelso Park on Sunday morning.
Hassan Vasit, the director of communications for Conservation Halton, told CBC News that the injured man was wearing a helmet on a man-made feature when he either fell off, or otherwise lost control of his mountain bike.
An Ornge air ambulance was called to the scene at 11:49 a.m. Within an hour, he had been transported to Hamilton General Hospital.
The man was reported by Ornge to have been in critical condition at the time that he was airlifted.