York Regional Police say the incident occurred as the amusement park's late-night "Halloween Haunt" event was wrapping up, at about 12:30 a.m., and people were walking to their cars.
One man died from his injuries on the scene. Another was rushed to hospital, where he remains in critical condition.
Homicide detectives would like to speak to anyone who was in the lot, near Jane Street and Springside Road in Vaughan, Ont., at the time. Contact the homicide unit at 1 (866) 876-5423 x 7865, or Crime Stoppers at 1 (800) 222-TIPS.