Montreal homicide investigators spent the night interviewing about 40 downtown party-goers after a 26-year-old man was found stabbed to death in an apartment at 1121 St. Catherine W. at about 3:50 a.m.

Police would not confirm the name of the victim but many people, including some who described themselves as relatives, later posted messages on social media mourning Bobby Pellicano, who worked in Montreal as a marine repairman, according to a friend.

Police said that the death occurred at a house party in an apartment above a commercial establishment under renovation near the corner of Stanley.

The 40-or-so people in attendance were questioned throughout the early morning as police sought leads in their investigation. Police also scoured the premises for physical evidence.

One witness who did not wish to be identified told CTV Montreal that the victim was stabbed after two men argued over a medallion that one of them was wearing.

Police did not reveal in which apartment the murder took place within the building where at least one unit rents for $15,000 per month.

"We're still trying to know what happened and what that conflict was about," said J.P. Brabant of the Montreal police.

He said that five people from the party who were transported to the detention centre for questioning to determine whether they were involved in the event or were witnesses to the event.

Names of those at the party are being cross-referenced against a list of known criminals and gang members but it's too early to determine whether gang disputes might have played a role in the killing.

The incident is the second homicide in Montreal of 2015. The first homicide dossier was opened Friday after a woman shot in 2010 finally succumbed to her injuries. Montreal also had two homicides at this time in 2014.