Hundreds of truckers clogging the streets of Canada’s capital stood their ground and defiantly blasted their horns Thursday as police poured in, threatening to break up the nearly three-week protest against the country’s COVID-19 restrictions.

Busloads of police arrived near Ottawa’s Parliament Hill, and workers put up extra fences around government buildings. Police also essentially began sealing off much of the downtown area to outsiders to prevent them from coming to the aid of the protesters.

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“The action is imminent,” said interim Ottawa Police Chief Steve Bell. “We absolutely are committed to ending this unlawful demonstration.”

Police made at least three arrests just before nightfall Thursday around Parliament Hill, but officers were not moving in force on the demonstrators. One of the organisers was seen in handcuffs between two police officers.

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Police continued negotiating with the protesters and trying to persuade them to go home, Bell said. “We want this demonstration to end peacefully,” he said, but added: “If they do not peacefully leave, we have plans.”

Many of the truckers in the self-styled Freedom Convoy appeared unmoved by days of warnings from police and the government that they were risking arrest and could see their rigs seized and bank accounts frozen.

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“I’m prepared to sit on my ass and watch them hit me with pepper spray,” said one of their leaders, Pat King. As for the trucks parked bumper-to-bumper, he said: “There’s no tow trucks in Canada that will touch them.”

Amid the rising tensions, truckers outside Parliament blare their horns in defiance of a court injunction against honking, issued for the benefit of neighbourhood residents.

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Ottawa represented the movement’s last stronghold after weeks of demonstrations and blockades that shut down border crossings into the U.S., inflicted economic damage on both countries and created a political crisis for Trudeau.

The protests have shaken Canada’s reputation for civility and rule-following and inspired similar convoys in France, New Zealand and the Netherlands.

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“It’s high time that these illegal and dangerous activities stop,” Prime Minister Justin Trudeau declared in Parliament, not far from where the more than 300 trucks were parked.

“They are a threat to our economy and our relationship with trading partners,” he said. “They are a threat to public safety.”

Ottawa police began locking down a wide swath of the downtown area, allowing in only those who live or work there after they pass through one of more than 100 checkpoints, the interim chief said.