There were four injuries, with at least 20 people involved in a bar fight early this morning on St. Denis near St. Catherine.
The fight took place inside the club and continued on the sidewalk, where someone pulled a knife.
Constable Dany Richer says of the four who were stabbed, one has been taken off the critical list.
"Four suspects were arrested, three men, one woman, all aged between 18 and 25 years old." said Richer.
"All victims and suspects are known to police."
There was also an attempted murder last night.
A man was shot and found bloodied and slumped in a car on St. Hubert near Mt. Royal east.
He's in critical condition in hospital.
There have been no arrests.