Canadian police cleared protesters and vehicles that had blocked a vital trade route on the border with the US, making some arrests, but the bridge was not yet open to traffic on Sunday.

The officers moved in after a tense standoff between Canadian police and demonstrators since Friday when a court order and threats of arrest failed to end the blockade of the Ambassador Bridge in Windsor, Ontario, which entered its sixth day on Sunday.

“Enforcement actions continue at the demonstration area with arrests being made. Vehicles being towed. Please continue avoiding the area,” Windsor Police said in a Twitter post early on Sunday, without saying how many had been arrested.

Police stepped up their presence with more than 50 vehicles, including cruisers, buses and an armoured car on Sunday, as the number of protesters dropped to around 45 from roughly 100 on Saturday.

US President Joe Biden has asked Canadian Prime Minister Justin Trudeau to use federal powers to end the blockade of the bridge, North America’s busiest land border crossing. Since Monday, protesters in trucks, cars and vans have blocked traffic in both directions, choking the supply chain for Detroit’s carmakers.