OTTAWA—For the first time in over three weeks, downtown Ottawa on Sunday was largely deserted, with the heavy-duty trucks and thousands of protesters demanding an end to Covid-19 vaccine mandates replaced by police vehicles, officers, and crews trying to clean up after a 23-day demonstration.

Officials in the capital and across Canada remained on high alert. While police in Ottawa cleared out Freedom Convoy protesters there, authorities in some of Canada’s biggest cities, such as Toronto and Vancouver, dealt Saturday with...

OTTAWA—For the first time in over three weeks, downtown Ottawa on Sunday was largely deserted, with the heavy-duty trucks and thousands of protesters demanding an end to Covid-19 vaccine mandates replaced by police vehicles, officers, and crews trying to clean up after a 23-day demonstration.

Officials in the capital and across Canada remained on high alert. While police in Ottawa cleared out Freedom Convoy protesters there, authorities in some of Canada’s biggest cities, such as Toronto and Vancouver, dealt Saturday with either the threat of a trucker-led demonstration or protesters that disrupted traffic.

“It’s still clear that while police have made significant progress, the job is not yet done,” Bill Blair, a former Toronto police chief and Canada’s emergency-preparedness minister, told CTV News on Sunday. “The threat, the risks, the reasons we had to invoke emergency powers, they still exist.”

On Saturday, police in Toronto said roads were closed in the downtown core after several heavy-duty vehicles tried to enter the city Friday night to cause disruption.

City workers cleaned up after protesters in front of Ottawa’s Parliament Hill Sunday.

Photo: andrej ivanov/Agence France-Presse/Getty Images

“Given the recent events in other cities, Toronto police have deployed a greater number of uniformed police officers to the downtown core,” a Toronto police spokeswoman said.

In the West Coast province of British Columbia, a convoy of vehicles on Saturday blocked a U.S.-Canada border crossing connecting Washington state with suburban Vancouver. Demonstrators were calling for an end to Covid-19 measures. The border crossing reopened late Saturday.

Mr. Blair, Canada’s emergency minister, said the Vancouver-area protest was evidence that the government’s emergency measures were necessary.

Prime Minister Justin Trudeau invoked extraordinary powers nearly a week ago under the country’s Emergencies Act that deemed the Ottawa protest and copycat demonstrations that blocked U.S.-Canada traffic as a threat to public order. A cabinet order said the Ottawa demonstration, and the U.S.-Canada border blockades it inspired, posed a national-security risk. The powers allowed police to create no-go zones, such as downtown Ottawa, and compel tow-truck drivers to remove trucks.

Lawmakers on Sunday continued debate in the legislature on a motion about the invocation of emergency powers, which are presently in effect but require parliamentary approval to be extended beyond a seven-day period. A vote is scheduled Monday night, and it is expected the Liberal government will have enough votes for the motion to pass.

People gathered to protest against Covid-19 measures in Surrey, British Columbia, on Saturday.

Photo: JENNIFER GAUTHIER/REUTERS

Police in Ottawa on Sunday cordoned off the immediate area surrounding the country’s parliamentary district, with the help of 10-foot fences and concrete barriers, and limited vehicular and pedestrian traffic into the area—for instance, to individuals with accreditation issued by the Canadian legislature. Cleanup crews picked up placards, and in one instance workers lifted a motorized wheelchair that protesters left behind onto the back of a pickup truck.

“This is not the normal state of our city,” said Ottawa police interim chief Steve Bell, of the need for fencing downtown. “Despite the successes of the past few days, we require these measures to prevent unlawful protesters from returning.”

Benoit Violette has lived in downtown Ottawa for over two decades, and he said he has seen his share of protests through the years. “I have never seen one that had such an impact on such a scale for myself and the other residents,” he said of the recent demonstration, which operated under the Freedom Convoy 2022 banner.

Mr. Violette said he’s an avid walker, and with the protesters gone, “I hope my morning walks will certainly be more peaceful.”

Interim chief Bell said he couldn't provide a timeline as to when traffic flow in the Ottawa core would return to normal.

Ottawa police said they have arrested 191 individuals since Friday, when officers commenced a surge aimed at forcing protesters and their vehicles to desert the protest encampment. Police said they have filed 389 criminal charges, mostly related to mischief and obstruction, towed 79 vehicles and cleared most downtown streets of heavy-duty trucks. Only a dozen protesters, some with a Canadian flag draped on their shoulders, milled about outside one of the fenced-off intersections.

Ottawa Mayor Jim Watson said Sunday the capital would continue to see a beefed up police presence for the immediate future, to ensure protesters don’t return and citizens’ safety can be secured.

“It’s like putting out a fire. You don’t want to have that one last ember that can light up again.”

Polling published recently from Angus Reid Institute indicated that over 70% of Canadians wanted the protesters to leave the capital.

Ottawa Mayor Jim Watson said Sunday the capital would continue to see a beefed up police presence for the immediate future.

Photo: andrej ivanov/Agence France-Presse/Getty Images

Write to Paul Vieira at paul.vieira@wsj.com