Reverend Claude Grou was celebrating mass at Montreal's landmark Saint Joseph's Oratory Friday, when a man in a baseball cap ran up to the alter.
He then rushed the priest who tried to run away.
The 77-year-old priest was stabbed after the man tackled him.
People rushed to the 26-year-old attacker, bringing him down.
They held onto him until police arrived.
According to the diocese, the priest's injuries were not severe.
So far, there's no word on why the priest was attacked.