Police said Lindsay Kantha Souvannarath, 23, of Geneva, Ill., and Randall Steven Shepherd, 20, of Halifax, will be in court Tuesday to face the charges after an intense investigation that began with a tip to Crime Stoppers.
A third person, a 17-year-old boy from the Halifax area, has been released without being charged due to a lack of evidence, but police said he remains under investigation. They said he was previously known to them, but offered no details.
A fourth suspect, a 19-year-old man, was found dead by police early Friday morning in the Halifax suburb of Timberlea.
RCMP Asst. Commissioner Brian Brennan said Saturday there is no indication the four suspects have any links to terrorist organizations, and that their motivation remains unclear.
"This group of individuals we would not define as a terrorist group," he said.
"Their friendship is not based on culture or ideology. They were four individuals who formed a friendship and decided to plan and commit a heinous crime."
Police Chief Jean-Michel Blais said the Halifax Shopping Centre in the west end of the city was the target of the alleged plot.
Brennan said three long-barrelled rifles were seized from the home where the deceased man was found, but wouldn't reveal what types of weapons they were.
None of the allegations made by police or other officials about the case have been heard or proven in court.
The investigation kicked into gear following a single, anonymous call to Crime Stoppers on Thursday morning from a Canadian source. Police say that led them to the home in Timberlea, a quiet Halifax suburb.
Brennan said the 20-year-old man was waiting to pick up the 23-year-old woman at the Halifax airport, where both were arrested at around 2 a.m. on Friday.
Police in Geneva said officers took multiple, unspecified items from her residence at the request of Canadian police.
Justice Minister Peter MacKay said earlier in the day that the unidentified 19-year-old and Souvannarath had been corresponding online, "with the goal of opening fire and committing an horrific of violence against us." Police would not elaborate on their relationship.
MacKay also insisted the alleged plot had no terrorist underpinnings, appeared to be random and without any specific philosophy, though he suggested the suspects could be radicalized.
"This appeared to be a group of murderous misfits that were coming here or were living here and prepared to wreak havoc and mayhem on our community," he said.
"An individual that would so recklessly and with bloody intent plot to do something like this, I would suggest would also be susceptible to being motivated by groups like ISIS and others."
Brennan refused to elaborate on the circumstances surrounding the man found dead in Timberlea, saying the issue has been referred to the province's Serious Incident Response Team, which reviews all serious incidents involving police in the province.
A statement from the team, known as SIRT, said police found the man dead when they entered the residence.
SIRT Director Ron MacDonald said Saturday the police watchdog will not release the name of the dead man but confirmed he was shot. There is no evidence he was shot by police, he said, adding part of their investigation is to determine how he died.
A police official, who was not authorized to speak publicly, told The Associated Press the young man shot himself to death after police surrounded his parents' home at around 1 a.m. Friday.
Police saw his parents leave the house and called the man. As the man told police that he didn't have any guns and he was on his way out of the house he shot himself, the official said.
A neighbour of the young man who was found dead said he hadn't mixed with others in the neighbourhood in recent years.
"He was one of those people who kept to himself, not a people person," said Steven Greenwood, 19.
His mother, Cindy Greenwood, 50, said there was a couple living in the house, but she couldn't recall meeting the younger man.
"It's a little scary to know this is just the next house down," said Greenwood, who woke up early Friday morning to the sight of police officers carrying guns outside her house.
"I just found out this morning what the plan was. ... That's scary."
A man in the house where the body was found came outside and asked reporters to leave, saying he had just lost his son.
Another resident said the family has lived in the neighbourhood for many years and the young man who died had attended the local school.
Greenwood said she felt badly for the family on her street.
"I can't imagine what the parents are going through," she added. "They are going through turmoil as well."
The case appeared to leave many jittery and an apparent false alarm triggered a large police presence at the Halifax Shopping Mall on Saturday.
Police said in an email there was "no active shooter situation" but seven youths who had a slingshot were taken into custody. There no immediate further details.
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