Numerous sources have told CTV Toronto that General Motors is planning to close all operations in Oshawa, Ont., affecting thousands of high-paying jobs.

The announcement is expected to be made on Monday, in the city of about 159,000 people located roughly 60 kilometres east of Toronto.

Sources say the Oshawa closures are part of a global restructuring aimed at moving toward lower-emission vehicles. Plants in the United States are also expected to close, although other GM operations in Ontario appear to be safe.

In an emailed statement to CTV Toronto, GM spokesperson David Paterson said the company “won’t be commenting ... on speculation.”

There are currently about 2,500 union positions and roughly 300 salaried employees in the Oshawa area. GM employs thousands more in Ingersoll, Markham and St. Catharines.

Unifor, which represents the hourly workers, said Sunday that it “does not have complete details” of the announcement but has “been informed that, as of now, there is no product allocated to the Oshawa Assembly Plant past December 2019.”

“Based on commitments made during 2016 contract negotiations, Unifor does not accept this announcement and is immediately calling on GM to live up to the spirit of that agreement,” the union’s statement said.

“Unifor is scheduled to hold a discussion with General Motors tomorrow and will provide further comment following the meeting,” the union added.

Federal Conservative Leader Andrew Scheer tweeted that his “heart goes out to all those affected by this devastating decision.”

A source with the federal government confirmed to CTV News that they are aware of the situation and concerned about Monday's announcement.

Conservative MP Erin O’Toole, who represents the riding of Durham, said on Twitter that, “from the calls I have been making tonight, it appears these reports about an end to vehicle assembly in Oshawa are true.”

“This is devastating news to families in Oshawa, the Durham region and all of Ontario,” O’Toole added. “Growing up, my father worked at GM much like the parents of many of my friends. I think of these families tonight and pledge to get to the bottom of why this is happening and whether the decision can be reversed.”

Oshawa MPP Jennifer French, a New Democrat, told CP24 that “if the news is true,” then Oshawa is “bracing ourselves for a fight.”

“Let’s be real here,” French said. “GM didn’t build Oshawa, Oshawa built GM.”

More than 100 years of history

GM’s history in Canada dates back more than 100 years. GM merged with McLaughlin Buicks in 1918. The Oshawa Assembly Plant opened in 1953.

By the early 1980s, more than 23,000 workers were employed at GM in Oshawa.

The Oshawa Assembly plant recently became the only factory in North America capable of building both cars and trucks.

Outgoing Oshawa Mayor John Henry told CTV Toronto’s Miranda Anthistle that he’s hoping the plant closure is “just a rumour” because GM is a “huge economic engine to the community.”

“My entire family has worked at General Motors,” said Henry. “My dad was a foreman in the plant. I have two brothers in the plant. My sister worked there in university. I worked there as a contractor.”

At the same time, Henry said that Oshawa’s economy has diversified so that it is no longer dependent on the auto industry.

“It’s very different now than when I was growing up, when everyone you knew was working in the plant,” he said.

“We’ve diversified and we have a lot of other things going on,” he added. “But the car industry is still a big part of our community.”

With files from CTV’s Glen McGregor, CTV’s John Vennavally-Rao and CTV Toronto’s Miranda Anthistle