Those who were in the area of Hess and Market Street in downtown Hamilton may have heard a loud “popping noise” at around 10 p.m. on Wednesday night.
Hamilton police say the noise was caused by a flare gun that was discharged during a fight between a group of men.
No injuries have been reported and police say the men fled before they arrived at the scene.
Hamilton Police Services say the Central Criminal Investigations Branch has taken over the investigation.
Anyone with information is being asked to contact Det.-Const. Alex Buck at 905-546-3816.
In Canada, it is illegal to fire a flare gun unless it is used exclusively for signalling or notifying distress.