James Topp, a Canadian Forces veteran who marched across Canada protesting against the coronavirus disease (COVID-19) vaccines mandates, arrives at the Tomb of the Unknown Soldier and the National War Memorial ahead of Canada Day in Ottawa, Ontario, Canad
James Topp, a Canadian Forces veteran who marched across Canada protesting against the coronavirus disease (COVID-19) vaccines mandates, arrives at the Tomb of the Unknown Soldier and the National War Memorial ahead of Canada Day in Ottawa, Ontario, Canada, June 30, 2022. Reuters / PATRICK DOYLE

The first in-person Canada Day celebrations in three years kicked off on Friday with a huge police presence and street closures throughout downtown Ottawa to prevent anti-government "freedom" protesters from disrupting the festivities.

Due to the COVID-19 pandemic, the free concerts and other activities usually held on the national holiday, which celebrates the founding of the country, were last held in 2019.

Prime Minister Justin Trudeau attended the start of the festivities with his wife and three kids. He shook hands with members of the crowd without incident, and in an interview with the Canadian Broadcasting Corp, said a difference in views was one of the country's strengths.

"The key on Canada Day is we don't just celebrate Canada, we celebrate Canadians. We celebrate each other, and that means listening to each other, respecting each other... That's part of the resilience of Canada," Trudeau said.

One of the protest organizers - Police on Guard for Thee - said on Twitter it had canceled an event billed as a family picnic after an altercation at the War Memorial resulted in four arrests Thursday.

James Topp, a former soldier and one of the organizers, had spoken at the War Memorial before the incident, but was not involved in the skirmish. Police said an officer had been choked and that it was investigating the scuffle.

Several groups have planned marches and even a dance party to protest coronavirus vaccination mandates, globalization and what they say is government overreach in Canada.

Some of the same organizers were behind a truck convoy that blocked Ottawa's downtown core around parliament for three weeks this past winter, causing a crisis that resulted in dozens of arrests. Separate protests during the same period snarled international travel and trade at border crossings.

Earlier this week, Ottawa's interim Police Chief Steve Bell said he expected hundreds of thousands of people to participate in the city's celebrations, though a much smaller crowd had gathered during the morning.

To keep vehicles from blocking the streets, most of the downtown core is closed to traffic, and officials are encouraging people to take free public transit instead of driving. The music and celebrations will end with fireworks in the evening.