Tonight, Canadians grieve for those killed in a cowardly attack on a mosque in Quebec City. My thoughts are with victims & their families. — Justin Trudeau (@JustinTrudeau) January 30, 2017

pic.twitter.com/KPeDuZD4V4 JUST IN: Video shows police in Quebec City responding to reports of deadly shooting at Mosque. https://t.co/OfIp2Nx1u9 January 30, 2017

QUEBEC CITY - Six people were killed and eight wounded when gunmen opened fire at a Quebec mosque during Sunday night prayers, in what Canadian Prime Minister Justin Trudeau called a "terrorist attack on Muslims."Police said two suspects had been arrested, but gave no more details into what prompted the "terrorist attack," saying the investigation had just begun.A witness told Reuters that up to three gunmen fired on about 40 people inside the Quebec City Islamic Cultural Center."Why is this happening here? This is barbaric," said the mosque's president, Mohamed Yangui.Quebec police on the scene said there had been fatalities and that two people had been arrested. Quebec provincial police were considering whether it was an act of terrorism, according to an intelligence source who declined to be identified. There were no immediate details on the suspects."There are many victims ... there are deaths," a Quebec police spokesman told reporters.A witness said a heavily armed police tactical squad was seen entering the mosque. A police spokesman declined to say whether there was still a gunman inside the mosque.Police tweeted later that the situation was under control and that the mosque had been secured and occupants evacuated.Yangui, who was not inside the mosque when the shooting occurred, said he got frantic calls from people at evening prayers. He did not know how many were injured, saying they had been taken to different hospitals across Quebec City."Tonight, Canadians grieve for those killed in a cowardly attack on a mosque in Quebec City. My thoughts are with victims & their families," Canadian Prime Minister Justin Trudeau tweeted.The shooting came on the weekend that Trudeau said Canada would welcome refugees, after US President Donald Trump suspended the US refugee program and temporarily barred citizens from seven Muslim-majority nations from entering the United States on national security grounds.New York Mayor Bill de Blasio said police were providing additional protection for mosques in that city following the Quebec shooting. "All New Yorkers should be vigilant. If you see something, say something," he tweeted.'NOT SAFE HERE'Like France, Quebec has struggled at times to reconcile its secular identity with a rising Muslim population, many of them North African emigrants.In June 2016, a pig's head was left on the doorstep of the cultural center."We are not safe here," said Mohammed Oudghiri, who normally attends prayers at the mosque but not on Sunday.Oudghiri said he had lived in Quebec for 42 years but was now "very worried" and thinking of moving back to Morocco.Mass shootings are rare in Canada, which has stricter gun laws than the United States, and news of the shooting sent a shock-wave through mosques and community centers throughout the mostly French-language province."It's a sad day for all Quebecers and Canadians to see a terrorist attack happen in peaceful Quebec City," said Mohamed Yacoub, co-chairman of an Islamic community center in a Montreal suburb. "I hope it's an isolated incident."Incidents of Islamophobia have increased in Quebec in recent years. The face-covering, or niqab, became a big issue in the 2015 Canadian federal election, especially in Quebec, where the vast majority of the population supported a ban on it at citizenship ceremonies.In 2013, police investigated after a mosque in the Saguenay region of the province was splattered with what was believed to be pig blood. In the neighboring province of Ontario, a mosque was set on fire in 2015, a day after an attack by gunmen and suicide bombers in Paris.Zebida Bendjeddou, who left the mosque earlier on Sunday evening, said the center had received threats."In June, they'd put a pig's head in front of the mosque. 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," she said.Bendjeddou said she had not yet confirmed the names of those killed, but added: "They're people we know, for sure. People we knew since they were little kids."