The OPP say their investigators have revealed the vehicle driven by the man and woman crossed over into the other lane “for unknown reasons” and collided head-on with an oncoming vehicle.
A 48-year-old man and a 26-year-old woman died as a result of the collision.
The three children and the driver of the other vehicle were taken to hospital.
OPP Const. Chad Murray said family members of the children were notified of the crash and are now involved.
Police have not publicly stated the ages of the three children.
The lone occupant of the second vehicle involved in the crash was released from hospital.
The collision took place on Longwoods Road in the municipality of Southwest Middlesex shortly before 6:15 p.m. Sunday.
Longwoods Road between Hagerty and Dogwood roads was closed for several hours after the crash, but has since been reopened.
The investigation into the crash is ongoing, Murray said. Anyone with information about the crash is urged to call OPP at 1-888-310-1122.