Canadian police say they have foiled a plot to carry out a mass shooting in the Halifax area yesterday.
Three suspects were arrested and a fourth reportedly shot himself dead after police surrounded his home.
At least two suspects had intended "to go to a public venue... with a goal of opening fire to kill citizens, and then themselves", police said.
Justice Minister Peter MacKay described those involved as "a group of murderous misfits".
"Based on what we know so far, it would have been devastating, mass casualties would have been a real possibility," he said.
"The attack does not appear to have been culturally motivated, therefore not linked to terrorism."
Brian Brennan, commanding officer of the Nova Scotia Royal Canadian Mounted Police, said the plot had involved a 19-year-old man from the Halifax suburb of Timberlea and a 23-year-old woman from the US state of Illinois.
The two, he said, had had access to firearms.
When police went to arrest the 19-year-old man he killed himself, a senior police official told AP news agency.
A 20-year-old Canadian man was arrested along with the woman at Halifax Stanfield International Airport. The fourth suspect, a 17-year-old Canadian boy, was arrested at a house.
The roles of the latter two suspects was still to be determined by investigators, police said.
'Obsessed with killing'
Mr Brennan said he would describe the alleged plotters as a "group of individuals that had some beliefs and were willing to carry out violent acts against citizens but there's nothing in the investigation to classify it as a terrorist attack".
"I can tell you that it's not culturally based," he added.
Police believe they have apprehended "all known individuals in this matter and eliminated the threat", he added.
According to the official who spoke to AP, the man who killed himself had told them he had no guns but he shot himself as he was coming out of the house.
The suspects had been on a chat stream and were apparently obsessed with killing and death and had many photos of mass killing, the anonymous official added.
Steven Blaney, the minister for public safety, said the arrests were a "great example of the fine work they do on a daily basis to help keep Canadians safe", Canada's CBC News reports.