Indigenous protesters east of Toronto on Wednesday halted all passenger trains between Canada's capital and the nation's two largest cities, Toronto and Montreal.
The rail corridors are the busiest in the country, and all seats had already been presold through to Thursday.
"Due to First Nations' railroad blockade, Via's train service on the Montreal-Ottawa-Toronto routes is interrupted," Via Rail said on its website.
Via Rail said it has arranged for train passengers to take buses instead to their destinations. It is also offering passengers refunds or credits for future travel.