An investigation is now underway to determine the cause and circumstances of a single-vehicle rollover on the Queen Elizabeth Way in Oakville that left a nine-year-old boy and its 38-year-old driver seriously injured.
The collision occurred shortly after midnight on Monday in the westbound lanes of the highway, approaching Burloak Drive.
On Monday, Sgt. Kerry Schmidt, of the OPP, said a pickup truck with three occupants inside, all of whom are related, entered the ditch and rolled over.
The 38-year-old driver of the vehicle, a resident of Hamilton, was transported to hospital with serious injuries.
A nine-year-old passenger was ejected from the vehicle and transported to hospital without vital signs. He was subsequently pronounced dead in hospital, police said.
Another passenger of the vehicle, a 28-year-old, was uninjured and remained at the scene, they added.