Father Claude Grou, rector of St. Joseph's Oratory of Mount Royal, was stabbed during a Mass March 22. The motive for the attack remains unknown.
He was taken to the hospital and was in stable condition, said a statement from the Archdiocese of Montreal.
During the 8:30 a.m. Mass in the crypt, a tall, light-skinned man wearing a white hat walked toward Father Grou and stabbed him in the stomach.
"At the end of the psalm, just before the ... Gospel, there is this guy who comes from who-knows-where -- I only film the front of the crypt -- and who moves rather quickly," said Dinh Khoi Vu, who directed the morning Mass at the Oratory for Salt and Light Television.
"Father Grou saw him coming with his knife. He had the reaction to move to the side, but he was still touched," he added.
"The knife fell. The aggressor was no longer able to pick it up. Many faithful rushed to hold him back. "
Father Grou got up, and members of the security service managed to control the attacker.
Fifty people were gathered in the crypt of St. Joseph's Oratory.
"Father Grou left the oratory, sitting in a wheelchair," to the applause of some people, relieved to see that he was still conscious, explained Vu. Father Grou left the oratory in an ambulance.
"He was sitting. He was conscious, "said Celine Barbeau, spokeswoman for the oratory.
Police closed the crypt and questioned witnesses.
Father Grou, 77, is a native of St. Laurent, Quebec. He joined the Holy Cross Congregation in 1966 and was ordained to the priesthood in 1968. He was elected as the congregation's superior general in 1986, an office he held until 1998. Since leaving that post, he has been working at St. Joseph's Oratory, Canada's largest church founded by St. Andre Bessette.
"We are all shocked by this act of violence that has taken place in our city, in a space dedicated to peace," Montreal Archbishop Christian Lepine said in a statement. "We know that places of worship of many religions are targets of acts of violence. We must continue to follow the path of peace and love, believing that good will overcome evil through prayer and good works."
Archbishop Lepine thanked the first responders to the scene, "especially those who courageously protected Father Grou."
He also encouraged everyone to "remain calm" and "continue celebrating their faith as a community."
Prime Minister Justin Trudeau tweeted his reaction to the assault: “What a horrible attack at St. Joseph's Oratory in Montreal this morning. Father Claude Grou, Canadians are thinking of you and wishing you a swift recovery."
Philippe Vaillancourt and staff at The Catholic Register in Toronto contributed to this story.
Francois Gloutnay is a reporter for Presence info, Montreal. Vaillancourt is editor of Presence info.