A convoy of Canadian truckers and their supporters began arriving in Ottawa on Friday to protest a federal government vaccine requirement for cross-border truckers and other coronavirus public health measures, as police warned of social media actors inciting violence and "lone wolf individuals" seeking to disrupt it.

Both Canada and the United States announced last year that they would require truck drivers entering their respective countries to be fully vaccinated. Canada implemented its measure Jan. 15, while the U.S. requirement started on Jan. 22. Most cross-border trade between the two countries occurs over land.

The convoy's size is unclear, and most of it is expected to arrive Saturday. Polls show vaccine mandates enjoy broad support here. Some 90 percent of Canadian truckers are vaccinated, according to the transport minister. The Canadian Trucking Alliance said it doesn't support protests "on public roadways, highways and bridges."

Prime Minister Justin Trudeau dismissed the convoy as a "fringe minority" this week.

It has drawn support from several federal Conservative Party lawmakers, Donald Trump Jr. and Tesla founder Elon Musk, a known opponent of vaccine mandates. Some Canadians have gathered on highway overpasses to cheer the convoy on.