Demonstrators against vaccine mandates halted traffic at two major border crossings in Western Canada and some vowed to stay even as Prime Minister Justin Trudeau used a law giving his government emergency powers to end blockades. 

The main border posts in Alberta and Manitoba were closed Monday, with commercial traffic to the U.S. blocked by semi-trailers and farm equipment driven there by people opposed to COVID-19 vaccine rules.

The crossings — one of which leads to Pembina, North Dakota and the other to Sweet Grass, Montana — are the second- and third-busiest for freight trucks along the western border of the two countries. They saw a combined 392,000 trucks enter the U.S. from Canada last year, according to data from the U.S. Department of Transportation. Both were still closed to commercial vehicles as of 12:14 a.m. New York time on Tuesday, according to Canada’s border agency. 

The protests started in reaction to Canadian and U.S. laws requiring truckers crossing the border to be fully vaccinated, but they’ve morphed into a rally against COVID restrictions. After a group of demonstrators blocked the Ambassador Bridge between Detroit and Ontario for six days, snarling trade, Trudeau invoked Canada’s Emergencies Act on Monday.