One person was airlifted to a Toronto area hospital in stable condition, police said, following a multi-vehicle collision in Orillia.
Ontario Provincial Police (OPP) say the crash happened around 5:30 p.m. Monday on Atherley Road at Creighton Street South.
The person who was airlifted to hospital had to be extricated from a vehicle by emergency crews.
Atherley Road was closed for several hours and has since reopened.
Police say a 45-year-old woman was arrested at the scene.
Charges are pending, they added, upon the results of the investigation.