Haldimand County OPP responded to a three-vehicle collision on Highway 6.
The call came in around 3:00 p.m. on Sept. 3, between the 10th and 11th concessions.
It was determined that a southbound vehicle had entered the northbound lane.
One man was pronounced dead at the scene.
Three other people suffered serious, life-threatening injuries and were transported to local hospital.
Highway 6 was closed for several hours as police conducted the investigation.
The names of the involved parties were not released.
It was not clear what caused the collision.