Wellington OPP are on scene of a serious collision on Concession 16 at Sideroad 15 in Mapleton.
The crash between two pickup trucks happened around 8 a.m. on Wednesday.
A man, 43, was airlifted to hospital with life-threatening injuries.
Two others were seriously hurt, and one person suffered minor injuries.
OPP say traffic will be diverted around the intersection between Arthur and Tiviotdale until later this evening.