Five students from the University of Calgary were stabbed to death at a house party in what has been described the worst mass murder in the city's history.

Matthew Douglas de Grood, 22, the son of a veteran Canadian police officer, has been charged with five counts of first-degree murder.

The motive for his attack against the victims aged between 22 and 27 is still unknown.

Police said the suspect had been invited to the party in the northwest residential neighbourhood of Brentwood, near the university campus to mark the end of the school year.

The suspect allegedly brought a weapon, or "instrument," from work to the party, but later grabbed a large knife from inside the house. He then "targeted the victims one by one, stabbing them several times", the police statement added.

Police chief Rick Hanson said: "We have never seen five people killed at one scene. The scene was horrific."

Three men were found dead at the home. A man and a woman died at a local hospital.

Students at the university were struggling to cope with the devastating news.

A vigil was held at the university late Tuesday was attended by about 500 students and faculty members.

The student's union president Raphael Jacob said: "This will continue to be a huge event in the history of the U of C and I think we just have to move beyond it together as a community."

He added: "I know many of my friends have been personally affected by this and it's scary. But don't be afraid to reach out and talk to someone."