Calgary police say they are "deeply concerned" after a woman in her 20s was shot and killed while standing outside a bar with friends.

Police say they were called to 11th Avenue and First Street S.W. around 3 a.m. MT for reports of a woman in distress.

Emergency responders say the woman, an innocent bystander, was shot outside Bronco Smokehouse & Saloon and died at the scene.

Police say she was with friends and family at the time of the shooting.

Sgt. Michael Cavilla with the Calgary Police Service said Saturday at a news conference that it was "purely a godsend" that more people were not hit by gunfire in the incident.

It's not known whether the gunman was on foot or in a vehicle but 12 people have provided witness statements to police so far.

The shooting is not believed to be gang-related and there is no suspect.