A 76-year-old woman from Toronto has died after a three-vehicle collision on Highway 401 in Milton Wednesday afternoon.

According to Ontario Provincial Police (OPP), the collision occurred around 3 p.m. in the eastbound lanes of the highway near Guelph Line.

OPP Sgt. Kerry Schmidt said that Ornge Air Ambulance was initially called to the scene to transport a victim who had sustained critical injuries.

“We did have Ornge Air Ambulance on the scene and ready to transport, but unfortunately those services were not required because of the injuries,” he said.

Schmidt confirmed that the victim was a passenger in one of the three vehicles involved in the collision.

“Sadly, a 76-year-old woman from Toronto was pronounced dead at the scene. The 79-year-old male driver was taken to hospital with undetermined injuries,” Schmidt said.

“The two other drivers from the pickup truck involved are all on scene speaking with officers, providing information, and they do not have any serious injuries to report.”

The cause of the crash is not yet known, but Schmidt said that it appears as though all three vehicles – two pickup trucks and a passenger vehicle – were in the same lane.

"Either traffic slowed down or something unexpected happened and that’s what we’re trying to determine right now while speaking to witnesses and involved drivers.”

The eastbound lanes of Highway 401 were closed between Guelph Line and Highway 25, but have since reopened.