Two people were taken to hospital after a late-night collision near Adjala-Tosorontio Township and Mono.
Ontario Provincial Police responded to the crash at the intersection of County Road 1 and Concession Road 3 at around 11 p.m. Friday.
Both people involved were transported to hospital with injuries that are not considered life-threatening.
Police say County Road 1 remains closed between Concession Road 2 and Concession Road 3, affecting the stretch between Hockley and Loretto.
The road closure is expected to remain in place while the investigation continues.