A 60-year-old man has been airlifted to hospital following a three-vehicle collision in Acton, Halton Police said.
The collision occurred at Highway 25 shortly after 9 a.m.
He was transported to Hamilton General Hospital with serious head and neck injuries, and is expected to be airlifted to another hospital.
The drivers of the two other cars were also transported to area hospitals. There is no word on the severity of their injuries.
Highway 25 is closed between 22 and 25 sideroads for the collision investigation.
CORRECTION: An earlier report said the crash occurred in Georgetown. The story has been changed to correct the error.