Nova Scotia RCMP Commanding Officer Brian Brennan said a man and woman planned to go to a public venue in the Halifax region on Feb. 14 "with a goal of opening fire to kill citizens, and then themselves."
Since then, three people have been arrested, one in Cole Habour, and two at the Halifax Airport. A fourth person was found dead in a house in Timberlea, N.S., just outside of Halifax. No charges have been laid.
Brennan said a tip helped them foil the mass shooting, but wouldn't provide more information about where the information came from.
Police notified one specific venue of the threat, but would not say what venue that was.
Brennan won't characterize the alleged plot as terrorism, but said the suspects "had some beliefs and were willing to carry out violent acts against citizens."
He didn't say what the beliefs were, other than that "they were not culturally based."
Justice Minister Peter MacKay has scheduled a news conference at 9 a.m. AT where he'll comment on the case.