Six people were killed and several wounded when three gunmen opened fire at the Quebec City Islamic Cultural Centre during Sunday night prayers.
The victims range in age from 35 to about 70.
Canadian Prime Minister Justin Trudeau said in a statement: "We condemn this terrorist attack on Muslims in a center of worship and refuge".
Canadian authorities said two suspects had been arrested, but they gave no further details.
Mexico's President Enrique Peña Nieto also condemned the attack and said that “Mexico stands in solidarity with Canada and the families of those who lost their lives in the Quebec City mosque.”