Officers were called to a Husky gas station parking lot at Upper Wellington and Limeridge Road around 3 a.m.
A 28-year-old man said he was approached by three men in balaclavas. At least one was armed with a weapon, police said.
They demanded he get out of the car before the trio got into it and fled.
Police are asking the public to keep an eye out for a 2008 Black Mitsubishi Lancer with the licence plate BYW F304.
Police believe the suspects are armed and the public should not approach the vehicle. If spotted, call 911.
Source: The Hamilton Spectator