[Ammi]

Five people have been killed at a house party in Calgary in what has been described as the city's "worst mass murder".

The son of a veteran Canadian police officer has been arrested in connection with the incident.

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

At least 20 people were at the party which was being held to celebrate the end of classes at the University of Calgary.

Police said the suspect was invited to the party and shortly after arriving picked up a large knife and began stabbing the victims one by one

Chief Hanson said the victims ages range from 22 to 27 and described them all as "good kids".

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

Hanson said the suspect brought a weapon, but used a knife from the house. He said there was nothing to indicate the suspect was drunk or had been doing drugs

He was arrested with the help of the police canine unit around 40 minutes after the incident.

Local resident Doug Jones said about a dozen students had been drinking beer around a firepit in the back garden of the house earlier in the night, but they were not rowdy

He said they all went inside by 9pm and he heard nothing after that.

University of Calgary President Elizabeth Cannon said "It's young people who have lost their lives at a very critical point in their lifetimes. It's a huge impact on all of us."