(CNN) While shocked parishioners and a television audience watched, a man stabbed the elderly rector of St. Joseph's Oratory at Mount Royal, Canada's biggest church, as he led Mass on Friday morning, Montreal police said.

Police said the stabbing was not considered a terrorist attack. "Today's event is an individual act committed by one individual," police said on Twitter.

The 26-year-old suspect was detained by security staff at the church and taken into custody by police, Chevrefils said. She said the suspect is known to police.

Grou was celebrating Mass for about 60 people in the church and an audience watching the event being livestreamed when the suspect went toward the priest and stabbed him several times with a sharp object, Chevrefils said.

Video showed Grou moving away as the man approached, then falling and getting up after the attack. Parishioners separated the attacker from the priest.

St. Joseph's Oratory in Montreal.

Police were called to the church at 8:40 a.m.

The suspect, whose name was not immediately released, is expected to appear by video feed at the Quebec Court Criminal Room about 1:30 p.m. Saturday. If any charges are filed, they will be determined by prosecutors, Chevrefils said.

Messages of sympathy filled social media.

"What a horrible attack at Saint Joseph's Oratory in Montreal this morning," Prime Minister Justin Trudeau tweeted . "Father Claude Grou, Canadians are thinking of you and wishing you a swift recovery."

What a horrible attack at Saint Joseph's Oratory in Montreal this morning. Father Claude Grou, Canadians are thinking of you and wishing you a swift recovery. — Justin Trudeau (@JustinTrudeau) March 22, 2019

Montreal Mayor Valerie Plante tweeted : "What a horrible and inexcusable gesture that has no place in Montreal. I am relieved to learn that the life of Father Claude grou, Rector of the @osjmr, is out of danger and that his condition is stable. On behalf of all Montrealers, I wish him speedy recovery. "

Christian Lépine, the archbishop of Montreal, posted a statement on the archdiocese website thanking police, paramedics and parishioners for their response.

"We are all shocked by an act of violence taking place here in a place dedicated to peace," Lépine said.