The Incident occurred about 7.50pm on Saturday, near the pedestrian crossing by Ilam School.
A woman and a man were stabbed by a second man, who then turned the knife on himself.
Detective Senior Sergeant Scott Anderson said those involved in the incident were known to each other, and that the Canterbury Police are not looking for anyone else in relation to the stabbing.
A student at the University of Canterbury, who didn't want to be named, was heading along Ilam Road towards the university's receration centre gym at 7.40pm when a car passed him, its occupants warning him that there had been a fight just up the road.
"At that point, there were no police around, or any real sense that anything was out of the ordinary," he said.
By 8:40pm, as he left the gym, police had arrived, blocking off Ilam Rd with cars and restricting entry.
"Pretty terrifying stuff, and incredibly sad too. Just awful."