Investigators have been told two men were placing rubbish in a skip at a Bradford Road school when a small black hatchback drove past about 10:15am on 2 June.
The car stopped and reversed towards the victims before a passenger in the car pointed what appeared to be a longarm firearm at the men.
Both victims took cover when the saw the gun and the vehicle sped off southbound on Bradford Road then turned left, east onto Morrish Road.
The gun was not discharged, and no one was injured as a result of the incident.
The passenger was perceived to be of Middle Eastern appearance, with a medium build, a black beard covering his jawline and was wearing a brown baseball cap.
The driver was also perceived to be of Middle Eastern appearance, with a solid build, black hair and a beard with no moustache.