A Canadian student known to have nationalist sympathies was charged with six counts of murder on Monday, over a shooting spree at a Quebec mosque - one of the worst "terrorist attacks" ever to target Muslims in a western country.
Alexandre Bissonnette was charged with six counts of premeditated murder and five of attempted murder, police said, noting more indictments are expected later.
The 27-year-old is a Quebec nationalist and anti-feminist who recently "liked" US President Donald Trump's page on Facebook and has also reportedly expressed support for French far-right politician Marine Le Pen as well as the Israeli military and other far-right groups.
Prime Minister Justin Trudeau condemned the "terrorist attack" on the Islamic Cultural Centre in a busy district of Quebec City, which sent terrified worshippers fleeing barefoot in the snow.
Eight people were also wounded in the attack, and five of them remained in critical condition in hospital Monday.
The Quebec mosque had already been the target of hate: a pig's head was left on the doorstep last June during the Muslim holy month of Ramadan.
Police stationed near the mosque told AFP that they had feared this type of attack "because it's happening all over the world."
Canadian police confirmed "there are search warrants underway."
"We hope to obtain the evidence to reach the point where we will be able to lay terrorism and national security charges," a spokeswoman for the Royal Canadian Mounted Police told a press conference.
So far, authorities have shed no light on what may have prompted the attack.
Both police and witnesses had initially described two masked men opening fire inside the mosque, where worshippers were gathered for evening prayer.
But on Monday, authorities said that a second person detained had only been questioned as a witness.
Explaining how one suspect was eventually let go, the RCMP said: "This morning and last evening we had reason to believe that two individuals should be arrested, that two people had participated."
After investigating, they said: "we reached the conclusion that we should focus on one single suspect. And there was no reason to believe that the other individual had participated."
Some 50 people were in the mosque at the time of the attack.
The dead are all dual Canadian nationals: one Moroccan, two Algerians, one Tunisian and two Guineans.
Public Safety Minister Ralph Goodale said the nation's security threat level remained at medium -- requiring security forces to be on guard but having no specific information about an imminent threat.
Police are continuing to collect evidence in a bid to "identify exactly who is involved and what was their motivation," Goodale said.
Authorities, he added, don't have "sufficient, hard facts yet to be able to draw conclusions."
The shooting came as Canada vowed to open its arms to Muslim refugees after Trump's controversial immigration ban prompted travel chaos and outrage around the world.
"Last night's horrible crime against the Muslim community was an act of terror committed against Canada and against all Canadians," Trudeau said.
To the one million Canadians who profess the Muslim faith, he said "36 million hearts are breaking with yours," alluding to the country's total population.