Prime Minister Justin Trudeau took the rare step of declaring a national public order emergency on Monday — allowing him to temporarily suspend civil liberties — in a push to end protests that have paralyzed the center of the Canadian capital for more than two weeks and reverberated across the country.

The move, the first time a Canadian government has taken such action in half a century, is Mr. Trudeau’s most aggressive response since the crisis began. It will allow the federal government to override civil rights to reopen impeded border crossings and clear the blockade of about 400 trucks in Ottawa, the nation’s capital, that has been overwhelming the police, snarling traffic, undermining the local economy and disturbing residents in the normally quiet city.

The invocation of the Emergencies Act confers enormous temporary powers on the federal government, allowing it to do what is necessary to restore public order, for example, banning public assemblies or restricting travel to and from specific areas. While the prime minister and the cabinet can invoke the act whenever they see fit if the security of Canada is deemed under threat, the decision must then be approved by Parliament within a week.

The protests have multiplied across the country, including an almost weeklong blockade of a bridge vital to the supply chains of the global automobile industry. The response by the police and all levels of government to the crisis has been widely criticized as inadequate.

Mr. Trudeau, some critics contend, should have intervened earlier and perhaps even sent in the army.

The decision to invoke the law came as the Royal Canadian Mounted Police in Alberta said it had arrested 11 people and seized a large cache of weapons, including 13 long guns, handguns and a machete, linked to protests in Alberta. Police officials said in a statement that the people arrested were linked to a small group near a border crossing in Coutts, Alberta — which has been blockaded for days — and that the group was willing to use force against the police if any attempts were made to disrupt its blockade.

The political optics of invoking the act are fraught for Mr. Trudeau, given that the measure allows the government to breach constitutional rights in the name of restoring public order. Mr. Trudeau, a Liberal, has long fashioned himself as a champion of human rights.

Mr. Trudeau’s extraordinary response brings back memories of October 1970 and a tumultuous period known as the October Crisis when Prime Minister Pierre Elliott Trudeau — Justin Trudeau’s father — quashed a wave of terrorism by a violent Quebec separatist group by invoking the War Measures Act, and then sending in troops to Montreal. It was the only time in Canadian history that the war act was applied in peacetime. The Emergencies Act was introduced in July 1988 to replace the war act.

While Mr. Trudeau has expanded his means to defuse the crisis, the most economically damaging part of the demonstrations appeared to have subsided. After protesters blockaded a critical economic link between the United States and Canada for nearly a week, traffic began making its way over the span again early Monday, providing some relief to the Canadian authorities struggling to tame the protests and to industries disrupted by the unrest.

But any sense of accomplishment by law enforcement at the Ambassador Bridge, which links Detroit and Windsor, Ontario, was offset by the tenaciousness of protests in Ottawa, which are now in their third week. Truckers have snarled traffic, disrupted normally serene residential neighborhoods and undermined the local economy.

The loosely organized “Freedom Convoy” demonstrations shaking Canada began as a protest against the mandatory vaccination of truck drivers crossing the U.S.-Canada border. But they have transformed into a battle cry against pandemic restrictions as a whole, and the leadership of Mr. Trudeau.

Doug Ford, the premier of Ontario, announced Monday morning that, as of March 1, the province will no longer require people show proof of vaccination to enter any indoor spaces. He stressed that the decision to rescind the so-called vaccine pass was based on the diminishing number of coronavirus cases and hospitalizations, and was not a concession to the demonstrators.

Canada has had among the toughest restrictions in the developed world, fanning growing frustration and fatigue as the pandemic has raged on.

A poll released Monday by the Angus Reid Institute, a leading polling organization, showed that, three weeks into the unrest, many Canadians do not support the protesters’ demands. Nearly 45 percentsaid the protests had made them more inclined to support indoor-masking requirements as well as vaccination requirements to cross the Canada-U. S. border, the polling organization said.

“If the goal of the Freedom Convoy was to capture the attention of millions of people in Canada and around the globe — mission accomplished,” the Angus Reid Institute said, but added: “If, however, the goal was to build support for their demands to end pandemic-related restrictions — it has backfired utterly.”

New details about the source of millions of dollars supporting the Canadian trucker convoy suggest many of the larger donors are wealthy Canadians, though one of the biggest contributions was made in the name of an American tech entrepreneur.

Leaked data said to be from the GiveSendGo crowdfunding platform, posted last night to a now-defunct web page by anonymous hackers, lists records of more than 92,000 donations totaling more than $8 million. A review of the data shows that some $4.3 million came from Canada, while another $3.6 million originated in the United States, though the United States accounted for the most individual donations. Small donations from dozens of other countries made up a fraction of the total amount raised.

One of the largest donations, for $90,000, is attributed to Thomas M. Siebel, a billionaire Silicon Valley entrepreneur and investor. He did not respond to a request for comment sent to the email address listed in the records and to his company.

Others who made donations ranging from $10,000 to $75,000 appear to be mostly Canadian business owners, with a few Americans in the mix.

Brad Howland, president of a New Brunswick-based company that makes pressure washers, appears in the leaked data as having donated $75,000, leaving the comment: “Hold the line!” In an email, Mr. Howland confirmed he was a donor, saying the protests “will go down in the history books.”

“Our company and my family are proud to stand with these men and women as they uphold the Charter of Rights and Freedoms of our great nation,” he said.

A donation for $17,760, attributed in the data to Travis Moore of Idaho, was accompanied by the comment: “Let freedom ring, brothers of the north. Cryptocurrency is the future.” A request for comment sent to Mr. Moore, using the email address listed in donation records, was answered with a reply containing a meme objecting to Covid restrictions.

Most of the comments left by donors expressed peaceful solidarity with the cause of opposing vaccine mandates and other pandemic restrictions. Mixed in with the positive messages, however, were some with a more menacing tone, like one left by an American who donated $50: “I’d rather pay to support this movement now than pay for bullets later.”

The presence of cryptocurrency evangelists among supporters of the convoy is apparent in a separate set of data reviewed by The New York Times. It shows donations were made in Bitcoin through a web page that went up after the initial fund-raising vehicle, GoFundMe, pulled the plug on the campaign. The new site, called “Bitcoin for Truckers,” is hosted by a cryptocurrency crowdfunding service, and had raised $946,000 as of Monday morning.

The Bitcoin campaign, which has received more than 5,000 mostly small-dollar donations, has been supported by a handful of large infusions from cryptocurrency boosters. The two biggest, with a combined value of more than $300,000 at the time they were made, were donated anonymously.

A series of others valued at about $42,000 each appear to be associated with an online challenge by a former software engineer who goes by the pseudonym LaserHodl and asked other Bitcoin fans to join him in supporting the trucker convoy. Jesse Powell, founder of the crypto exchange Kraken, tweeted his agreement, and a donation attributed to him appears in the data.

Benjamin Dichter, one of the convoy organizers, said at a news conference last week that after the cryptocurrency crowdfunding campaign began, he received offers of help from “major players” in the crypto markets.

“I was shocked how quickly I started getting messages from some of the most prominent Bitcoiners in the world,” he said.

The GiveSendGo data leak was announced Sunday evening on a webpage titled “GiveSendGo IS NOW FROZEN,” with a five-minute video in which a manifesto by the anonymous hackers scrolled across the screen. In it, the hackers complained that the trucker protest had “held a city hostage” and warned it “could be cover for a type of Trojan horse attack where extremists and militia groups may arrive in large numbers with weapons.”

The data contains a record for each donation that includes the donor’s name, ZIP code and the email address they used. It is not possible to independently verify every donation, but some of them line up with donations that had publicly appeared on the GiveSendGo website before it went offline.

For example, Mr. Siebel was cited last week by a Canadian news network, which noted that his name appeared with the $90,000 donation, at the time it was made, on the web page for the convoy campaign. About half the donations were not accompanied by a person’s name when they publicly appeared on the page.

GiveSendGo, which had earlier been the target of another data hacking that revealed personal information, such as driver’s licenses and passports, for some site users, was offline Monday morning. The company did not respond to a request for comment.

Organizers started a GiveSendGo campaign earlier this month after GoFundMe shut down an online fund-raiser that had raised nearly $7.8 million. The funds were to be used to “provide humanitarian aid and legal support for the peaceful truckers and their families,” Alex Shipley, a spokeswoman for GiveSendGo, told The Times in an email last week.