Political and religious leaders gathered in Quebec City Monday morning to denounce a deadly terrorist attack at a mosque.

Saying there were no divisions, no political parties among the people standing with him, Quebec City Mayor Regis Labeaume said his city would host a vigil at 6 p.m.

"We will ask our friends, our community, what we can do to reduce the hurt, to ease their pain," said Labeaume.

Flags have been lowered to half-mast across Quebec to honour those slain, with Premier Philippe Couillard ordering the flag lowered at the National Assembly, and municipal leaders following suit.

"We are all one people, indivisible on this day," said Couillard.

"The goal of this meeting is to hear from the community, not from us," he added, before speaking a blessing in Arabic.

Community and religious leaders then spoke, one by one, about the attack and how people must not let themselves be torn apart by hate.

"Words fail us in this situation to express the pain that we feel because we lost men, men who started their lives in this wonderful country," said Boufelja Benabdalla, co-founder of the Quebec Islamic Centre that was attacked on Sunday.

"But we also have no words to express our solidarity with the mayor, the premier, the solidarity they show with us."

"It honours us, and shows that we are all citizens together," said Benabdalla.

Mohamed Labidi said he could not believe that gunmen attacked people in the midst of prayer.

"I heard from a witness who escaped," said Labidi.

"Those who were shot the most were those who were standing in prayer. Truly, truly this is a tragedy."

Couillard later added that Quebecers have to resist those who seek to sow hatred and division.

"Spoken words matter. Written words matter. They can of course express an idea, but they can hurt. They can hurt very much. We should all be cognizant of that," said Couillard.

"This is why our country, in Canada and Quebec, our nation of Quebec here, have to remain a beacon, a landmark of tolerance and openness in this troubled world."

The real challenge, he added, would be to maintain this tolerance and acceptance in the weeks and months to come.

Montreal Mayor Denis Coderre also lent his support at a news conference in Montreal, saying we must unite and fight Islamophobia.

Visibly moved, Coderre said he would attend the vigil in Montreal.