A shooting at a Quebec mosque during Sunday night prayers which killed six people was a terrorist attack, ABC News quoted Canadian Prime Minister Justin Trudeau as saying on Monday.
"We condemn this terrorist attack on Muslims in a centre of worship and refuge," Trudeau said in a statement.
A Quebec police spokesman said six people died in the attack and eight people were injured. Police said two suspects were arrested.
A witness said heavily armed tactical police entered the mosque, but a police spokesman declined to say whether there was a gunman inside.
Earlier, a witness told reporters that up to three gunmen fired on about 40 people inside the Quebec City Islamic Cultural Centre.
Yangui, who was not inside the mosque when the shooting occurred, said he got frantic calls from people at evening prayers.
He said the injured had been taken to different hospitals across Quebec City.
Quebec Premier Philippe Couillard said it was an act of "barbaric violence" and expressed solidarity with victims' families.
Zebida Bendjeddou, who left the mosque earlier on Sunday evening, said the centre had received threats.
"In June, they'd put a pig's head in front of the mosque," she said.
"But we thought: 'Oh, they're isolated events'. We didn't take it seriously. But tonight, those isolated events, they take on a different scope."
Incidents of Islamophobia have increased in Quebec in recent years amid a political debate over banning the niqab, or Muslim face covering.
In 2013, a mosque in the Saguenay region of Quebec was splattered with what was believed to be pig blood.
In the neighbouring province of Ontario, a mosque was set on fire in 2015, a day after an attack by gunmen and suicide bombers in Paris.