WINDSOR, Ontario — Canadian police have moved in to remove protesters who have disrupted Canada-US trade at a major bridge border crossing, though several trucks remained blocking traffic.

Many protesters began driving away as police approached the Ambassador Bridge, which connects Detroit and Windsor, shortly after dawn.

They had spent the night at the busiest crossing between the United States and Canada despite new warnings to end the blockade that has disrupted the flow of goods between the two countries and forced the auto industry on both sides to roll back production. But three large trucks and about 20 protesters remained blocking traffic early Saturday, and they began singing Canada’s national anthem.

The "Freedom Convoy" protesters have been disrupting travel at U.S.-Canada border crossings for the last week. The protesters have blocked roadways with tractor trailers in a demonstration against Canadian regulations that require truckers entering the country to be vaccinated against COVID-19 or submit to regular testing.

The protests at the Ambassador Bridge have been particularly devastating to the supply chain. The bridge is among the busiest border crossings in North America and is responsible for 25% of all trade between the United States and Canada.

According to the bridge company, nearly 8,000 trucks carry more than $323 million in goods across the bridge every single day. About $100 million of that is auto parts, engines and vehicles.