A typically bustling border crossing between Windsor, Ont., and Detroit remained closed to vehicles seeking to enter Canada on Tuesday as a protest against COVID-19 measures prevented traffic from flowing.

Windsor police said they negotiated the resumption of U.S.-bound traffic across the Ambassador Bridge earlier in the day and were focused on communicating clearly with demonstrators on the Canadian side who caused all travel to stop for a period of time the previous night.

"Our focus is on maintaining open communications with organizers of the demonstrations and using a reasoned, tempered approach, including the appropriate use of police discretion to guide our police personnel's responses," the force said in a written statement. 

Police redirected commercial traffic to the Bluewater Bridge in Sarnia, Ont., and urged motorists to avoid the area around the Ambassador Bridge. 

The force, which had a heavy presence near the bridge, also issued a warning to demonstrators.

"We want to urge those involved in illegal activity not to endanger members of the public or first responders, including police personnel, and jeopardize public peace," police said. "Those found committing crimes and acts of violence will be investigated and charges will be laid."

Windsor Mayor Drew Dilkens had his own warning for demonstrators. 

"Blocking the international border crossing will not be tolerated for very long," he said in a phone interview.

Dilkens said he wanted at least one lane reopened to allow traffic into Canada.

The closure is also difficult for local residents, who have expressed their frustration at the situation, he said.

"I, like many, just want to see these people go away, and I'd love to go in there and round them all up and throw them in jail," Dilkens said. "But that's not sensible, that's how I viscerally feel."

The bridge is considered the busiest international commercial land border crossing in North America.

"A full third of our international trade with the United States crosses at Windsor-Detroit," the mayor said. "It's 8-to-10,000 trucks a day and depending on the day, $300 to $500 million crossing there every day." 

That includes the tightly intertwined supply chain of the automotive sector between the two cities.

"What's not OK is using your protest to cause economic damage to Canada, to Ontario and to our region," Dilkens said. "Because what you're actually doing is hurting innocent families who require smooth and efficient border crossings to put food on their table."

The demonstration impeding travel at the bridge was one of several in solidarity with a similar protest in Ottawa.

Federal Transportation Minister Omar Alghabra said blockades, including the one affecting the Ambassador Bridge, will have serious implications on the Canadian economy.

"This is really serious cause for concern," Alghabra said in Ottawa on Tuesday. 

Alghabra said he'd offered his assistance to his provincial counterpart but noted that the protest near the Ambassador Bridge was a policing matter for the city and for the province to address. 

Federal Emergency Preparedness Minister Bill Blair said the bridge was "a vital artery of supply and services" for Ontario.

"It’s one thing to protest, but when that protest ... impacts so significantly the people of Ontario, I think it does require an appropriate response," he said at a news conference.

Ontario Premier Doug Ford also noted that the Ambassador Bridge is a key trade crossing point between Canada and the United States. 

Asked about the impact of the protests on trade, White House press secretary Jen Psaki took pains to note that any congestion at Canada-U.S. border crossings was a result of the protests themselves, and not of the vaccination mandates some international truckers are complaining about.

"What we’ve seen with these requirements is across industry, a range of industries, vaccination requirements have been implemented with no disruptions and have helped increase vaccinations," Psaki said. 

"These requirements help protect more people from COVID, and there’s been zero indication across these industries that they would lead to disruptions."

The White House is in touch with federal officials in Ottawa about the situation, she added.

"We, of course, support the right to freedom of speech and protest. But while we do see some of this congestion due to protests, it’s clear that these disruptions have broadened in scope beyond the vaccine requirement implementation."

The chairman of the Detroit International Bridge Company, which owns the Ambassador Bridge, called on officials to "take prompt action" to resolve the situation quickly.

The Michigan Department of Transportation advised those headed to Canada to use the Port Huron crossing, which connects that American city with Sarnia, Ont.

Meanwhile, protesters in southern Alberta resumed their blockade of the Coutts border crossing Monday evening, where trucks and other vehicles began parking on the highway on Jan. 29, stranding travellers and cross-border truckers for days.

- With files from James McCarten in Washington.

This report by The Canadian Press was first published Feb. 8, 2022.

Maan Alhmidi and Liam Casey, The Canadian Press

Note to readers: This is a corrected story. An earlier version said the protest at the Coutts crossing began Feb. 5.