TORONTO -- Police say a 48-year-old Toronto man is dead after being struck by a vehicle while trying to change a flat tire on the southbound Highway 400 in the city's northwest end.

The man was pronounced dead at the scene near where Highway 400 meets Highway 401 just after 3 a.m. Friday.

OPP Sgt. Kerry Schmidt says the man had stepped out of his car to change a tire on the front driver's side.

He says the man had turned on the car's four-way flashing hazard lights and moved it entirely onto the shoulder but it appears the vehicle that struck the man had crossed the line into the shoulder.

The southbound lanes of Highway 400 at Black Creek Drive were closed for several hours while police investigated but they say all lanes have since reopened.

Schmidt advises drivers in similar situations to try to move as far from fast traffic as possible, or stay in the car and call 911 for help.

"It's a hard situation, because with a flat tire you can't go too far," Schmidt said of Friday's incident.

The victim's name is being withheld until his family can be notified. Police say the driver of the second vehicle was taken to hospital with minor injuries.

Also on Friday morning, a man was struck and killed by a vehicle in Mississauga (on Winston Churchill Boulevard south of Britannia Road) just before 5:30 a.m.

It's the fourth pedestrian fatality on roads in the Greater Toronto Area in the past few days.