11/10/2013 04:15 EST | Updated 01/23/2014 06:58 EST

Toronto man shot dead while celebrating 20th birthday

A Toronto man was killed overnight while celebrating his birthday with friends in the east-end building where he lived with his family, police say.

Toronto police Det. Sgt. Justin Vander Heyden told reporters that Gaethan Kitadi was shot in the back on the day he turned 20.

"Mr. Kitadi was born on today’s date and he was 20 years old as of today," Vander Heyden said Sunday.

The shooting happened at the building located at 11 Main St., near Kingston Road. The victim lived there with his family, though he was celebrating his birthday at a friend’s apartment.

Vander Heyden said the party had been promoted on social media, though the people who organized the event were very careful about who was admitted to the building.

"Only people that were on a guest list were allowed to arrive," he said.

That has led police to conclude the people involved in the conflict were known to someone at the party.

"They were granted access to the building, so somebody in that group knew them," Vander Heyden said.

Police say a group of people arrived at the building shortly after midnight. Vander Heyden said that about 15 minutes later, a lot of people from the party moved to the lobby and vestibule of 11 Main St.

"What is obvious is that there is some kind of conflict between Mr. Kitadi, his friends and another group of people," Vander Heyden said.

He said "a great deal of the conflict" was captured on surveillance cameras at the building.

Though it is believed Kitadi was shot in the back, Vander Heyden said that must be confirmed in a post-mortem.

"It looks as though Mr. Kitadi turned to leave — I’m not sure if he saw a gun and attempted to flee, but he was shot in the upper body," he said.

Kitadi collapsed close to the spot where he was shot. Vander Heyden said he was pronounced dead at the scene.

So far, police have recovered physical evidence from the crime scene, though Vander Heyden said a weapon has not been found.

Vander Heyden said Kitadi had "no contact with Toronto police" prior to his death.

"Mr. Kitadi clearly didn’t leave a lifestyle that would lead him into this," he said. "It looked like he was trying to eject people from his own building, which was well within his rights."

Police ask the people present at the party to make contact with investigators.

"We’ve had some co-operation from other people in the party who allowed us to have access to their photographs that they took that night, and I have in excess of 100 different photographs of people who were at the party," said Vander Heyden.

"Unfortunately, I’ve only had a very small number of people come forward and speak to us about what had happened."