Toronto police are appealing to witnesses to come forward after a man was killed in the lobby of his own building. Police say it appears the victim was shot, just minutes after he turned 20, when unwelcome guests turned up at his party.

Gaethan Kitadi was shot in the back around 12:30am early Sunday morning at his apartment near Main Street and Kingston Road where he lives with his parents and siblings, Det.-Sgt. Justin Vanderheyden said at a Sunday afternoon news conference.

According to Vanderheyden, Kitadi was celebrating his birthday with a group of 20 to 30 people in his home.

Shortly after midnight, surveillance footage of the lobby shows two or three young men arriving at the building, Vanderheyden said. There appeared to be no confrontation between the men and several partygoers gathered in the lobby, he added.

Just minutes later, a group of eight men, including Kitadi and the men who had arrived earlier, are seen on the footage exiting the elevators to the lobby of the building, Vanderheyden said. As the men walk to the doors, Vanderheyden said it appears a physical confrontation breaks out between some of the men and Kitadi. The footage shows Kitadi turning his back to the men and then a shot is fired, hitting Kitadi’s upper body.

Vanderheyden said it appears Kitadi was attempting to escort the men out of the building just before being shot. He says police and EMS arrived shortly after the incident, but efforts to revive Kitadi were unsuccessful. He was pronounced dead at the scene.

Vanderheyden said police were met by "very upset and concerned friends of Mr. Kitdai's" at the apartment, and emergency workers “had to push and fight their way to find him.” He called it a “chaotic scene” and many partygoers left before talking to police.

"I don’t really blame them for leaving and trying to seek some peace somewhere else," Vanderheyden said. "But now, the next day, there’s a murderer out there and we need to find him and these people. I guarantee you, they have the answer to many of my questions."

Vanderheyden said a "great deal" of the incident is captured on footage, but it is hard to tell exactly “who did what.” He said it’s vital for police to get more information from witnesses surrounding the events that led to the shooting, adding that if witnesses do not come forward, police might release the video footage of the incident.

Vanderheyden said it’s not clear if the men who arrived at the building just after midnight made their way into Kitadi’s apartment or remained in the halls of the building. He added that there was a guest list to the party on social media, but believes that either Kitadi or someone else at the party likely knew the men.

Toronto police are looking for two persons of interest. Vanderheyden described the first as a black male in his late teens or early 20s who was wearing a white hoodie with a black baseball cap and dark pants. The other is described as a black male of the same age wearing a puffy black jacket with a blue hoodie underneath along with white shoes.

Vanderheyden said Kitadi was not known to Toronto police. This is Toronto’s 52nd homicide of the year.