A manhunt for suspects is underway after a botched armed robbery on a major 400-series highway in the GTA.

Mississauga OPP were called to 410 from Brampton just after 8pm on Tuesday.

The victim said she was rear-ended by a red car.

When he stopped between Sandalwood Parkway and Mayfield Road, police say he was robbed by three to four suspects.

One had a knife and another a gun.

If you saw the robbery or have information, you can call police at 1-888-310-1122 or Crime Stoppers at 1-800-222-8477 (TIPS).