Peel police are investigating a shooting on the eastbound Highway 403 ramp to the Highway 401 collectors that sent two people to hospital.
It happened just after 11 p.m. on Sunday.
Toronto police initially said they received the call from a woman who said her friend was struck as shots were fired from another vehicle.
They said the woman drove to a local hospital and was treated for a minor hand injury.
Police said a man was taken to a trauma centre with a serious gunshot wound.
Police later confirmed both victims were male — a 32-year-old man from Mississauga and a 43-year-old man from Brampton.
There has been no word on what prompted the shooting or a suspect description.
The ramp was closed while police investigated but has since reopened.
This is the second time in four days that shots have rung out on a 400 series highway.
On Thursday, a male was shot at on the 401 near Keele Street, but no injuries were reported.
The gunman in that incident was believed to be inside a dark coloured Honda.