A Catholic priest celebrating morning mass on Friday was stabbed by a man at Montreal's landmark Saint Joseph's Oratory.
The mass was being broadcast live on the internet.
Father Claude Grou, who is the church rector, was wounded in the upper body and transported to a hospital, according to the Catholic diocese. He is "slightly injured. We do not fear for his life," tweeted Jasmin Lemieux-Lefebvre, director of communications for the Catholic Church of Quebec.
A suspect was held by the church's security service and later arrested by Montreal police, said the force.
Saint Joseph's is in Montreal's Mount Royal district and Canada's biggest church.