Niagara Regional Police are asking for the public's help in identifying four men connected to the shooting in downtown St. Catharines early Sunday morning.

On Monday afternoon, police released security video footage showing four black men walking on St. Paul Street toward Ontario Street at about 1:40 a.m., about the same time of the shooting that sent one person to hospital.

One of the men, seen on right side of the video wearing a tracksuit with a white stripe on the arm, matches the description of the gunman released by police Sunday.

Police spokesperson Stephanie Sabourin said the men are "persons of interest" to police detectives.

Officers were called downtown Sunday after a shooting took place in the area of St. Paul and Queen streets. A 24-year-old man with life-threatening injuries was found on scene. He was taken to a local hospital before being moved to an out-of-town trauma centre.

On Sunday police said the gunman was wearing a dark blue hooded athletic tracksuit with a solid white stripe down the side of his jacket and pants.

Sabourin said police have not connected Sunday's shooting with a Sept. 5 shooting at Church and Niagara streets which sent three people to hospital. No arrests have been made in that case.

Sabourin said the same team of detectives are working on both cases and if there are connections they are well placed to find them.

Police are asking witnesses to call 905-688-4111 ext. 9046 or Crime Stoppers at 1-800-222-TIPS