OTTAWA, Ontario — Tensions rose in Ottawa on Wednesday as police trying to break the nearly three-week siege of the capital by truckers protesting Canada’s COVID-19 restrictions began warning drivers to leave immediately or risk arrest.

At the same time, protesters abandoned their last remaining truck blockade along the U.S. border — at Emerson, Manitoba, opposite North Dakota, police said. With that, all border crossings were open for the first time in more than two weeks of unrest.

In Ottawa, authorities in yellow “police liaison” vests went from rig to rig, knocking on the doors of the trucks parked outside Parliament, to hand truckers leaflets informing them they could be prosecuted, lose their licenses and see their vehicles seized under Canada’s Emergencies Act. Police also began ticketing vehicles.

Some truckers ripped up the order, and one protester shouted, “I will never go home!”

Some threw the warning into a toilet put out on the street.

Protesters sat in their trucks and defiantly honked their horns in a chorus that echoed loudly downtown.

At least one trucker pulled away from Parliament Hill.

There was no immediate word from police on when or if they might move in to clear the hundreds trucks by force. But protest leaders braced for action on Wednesday.

“If it means that I need to go to prison, if I need to be fined in order to allow freedom to be restored in this country — millions of people have given far more for their freedom,” said David Paisley, who traveled to Ottawa with a friend who is a truck driver.

Marie Eye, of Victoriaville, Quebec, who has been making soup for the protesters, said the warnings were “just a piece of paper” and doubted police had the manpower to remove the rigs or the protesters.

The warnings came just days after Prime Minister Justin Trudeau invoked the emergency law.

“It’s not for politicians to tell police when and how to do things. What we have done with the emergency act is to make sure the police have the necessary tools,” Trudeau said Wednesday. “It’s something that I, like all residents of Ottawa, hope to happen soon.”