Prime Minister Justin Trudeau says the federal government is reviewing its handling of refugee claims in the wake of the Edmonton attacks.
He says Ottawa is trying to find out what happened in the case of the Somali refugee accused of carrying out the violence, which injured five people.
American authorities say he had been ordered deported from the U-S in 2011, but failed to show up for a hearing in January 2012.
Later that year, he arrived in Canada and was cleared as a refugee.