Prime Minister Justin Trudeau and Alberta Premier Jason Kenney were seated beside each other at a memorial in Edmonton for victims of last week's downing of a Ukrainian jetliner in Iran.

Kenney says the people on the jet were victims of "a chain-reaction, rooted in the human failure to resolve conflicts peacefully."

Prime Minister Justin Trudeau says he wants to assure all Canadians that his government will not rest until there are answers, justice and accountability for the downing of Ukraine International Airlines Flight 752.

Trudeau told a memorial service attended by thousands in Edmonton on Sunday that Canadians were first heartbroken to learn of the crash that killed 57 Canadians and dozens more with ties to Canada, and were "shocked and outraged'' when they heard it was brought down by an Iranian missile.

After initially insisting Iran's military had no role in the crash, Iranian President Hassan Rouhani admitted in a tweet early Saturday that the plane was mistaken for a hostile target and accidentally shot down minutes after taking off from Tehran's international airport.

Trudeau told the vigil that Canada will continue to work with its partners to ensure that a full, transparent investigation is conducted.

"No words can erase the pain of those grieving, but it is my sincere hope that you can find some comfort in knowing that all Canadians stand with you," Trudeau says in an online post. "You are not alone, and we will continue to stand with you in the days, weeks, months, and years to come."