Pope Francis has condemned the Quebec mosque attack that left six dead and eight injured and said he is praying for the victims and their families.

ABC News reports that the pontiff expressed his condolences to the archbishop of Quebec, Cardinal Gerald LaCroix, who was in Rome on Monday and returned immediately to Canada.

Francis said he is praying for those killed and injured, as well as those who responded to the bloodshed. He wrote, "The Holy Father firmly condemns the violence that engenders such suffering, and begs the Lord for the gift of mutual respect and peace."

In a separate statement, the Vatican's office of relations with Muslims is condemning the act of "unheard of violence," saying a massacre at a mosque "violated the sacredness of human life and the respect owed to a community in prayer in a place of worship."

"The pope underlined how important it is in these moments that everyone remains united in prayer, Christians and Muslims," the Vatican said.

Two suspects, identified as Mohamed Khadir and Alexandre Bissonnette, shouted 'Allahu akbar!' as they opened fire at the Quebec Islamic Cultural Center Sunday night, killing six. Five people were in critical condition and 12 others suffered minor injuries, University of Quebec Hospital Center spokeswoman Genevieve Dupuis said Monday.

Those killed included father of four, the owner of a halal butcher near the mosque; the mosque concierge; and Ahmed Youness, a 21-year-old student, according to Reuters.

Shortly after the attack, one gunman turned himself in, calling 911 and giving officers his location in d'Orleans so they could arrest him, police said. Both suspects are currently in custody, and one is confirmed to be of Moroccan origin.

While police say a motive was "unclear," Prime Minister Justin Trudeau was quick to condemn the attack as a "terrorist attack on Muslims."

"We condemn this terrorist attack on Muslims in a center of worship and refuge," he said in a statement. "Muslim-Canadians are an important part of our national fabric, and these senseless acts have no place in our communities, cities and country."

French President Francois Hollande condemned the attack, stating: "The terrorists wanted to attack the spirit of peace and tolerance of the citizens of Quebec. France stands shoulder to shoulder with the victims and their families".

According to reports, the mosque was previously targeted in an Islamophobic attack. During during Ramadan of last year, a pig's head was left on the mosque's doorstep along with a note that said "bon appetit".