Police Chief Rick Hanson says the suspect is a student at the University of Calgary and was an invited guest at a house party celebrating the end of the school year.
Hanson says the suspect arrived at the party early this morning, got his hands on a knife and began stabbing the victims one by one.
Three men died at the scene, while another man and a woman died in hospital.
Hanson says the dead were all "good kids" who ranged in their twenties.
Hanson says first-degree-murder charges are pending and the name of the suspect will be released after they are laid.