Police say they are looking for a possible motive and a fourth person in connection with the fatal shooting of a bystander early Saturday morning in downtown Calgary.

Three people are in custody after being arrested at a hotel in the city's northwest, police said on Monday.

Police say the three people are known to Toronto police and one is wanted on a Canada-wide warrant for attempted murder. However, Calgary police say there is no connection between the suspects and the shooting victim.

Police said they are also seeking a black man, believed to be about 20 years of age, about five feet 10 inches tall and weighing approximately 160 pounds.

According to police, the suspect often wears a gold medallion around his neck.

Police identified the victim as Natasha Mohamed Farah, 26, who had moved to Calgary from Toronto about a year ago.

Calgary police are looking for this man in connection with the fatal shooting of a bystander in downtown Calgary over the weekend. (Calgary Police Service)

Gunfire was reported at approximately 3 a.m. MT on Saturday morning at 11th Avenue and First Street S.W. outside Bronco Smokehouse and Saloon.

When officers arrived on the scene, they found the woman suffering from a gunshot wound. She was pronounced dead at the scene.

A suspect vehicle that was observed leaving the scene of the shooting has been identified and located.

Investigators would like to speak to witnesses who were in the area in the early morning hours of Saturday.