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.

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 鈥渨on鈥檛 be commenting ... on speculation.鈥

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 鈥渄oes not have complete details鈥 of the announcement but has 鈥渂een informed that, as of now, there is no product allocated to the Oshawa Assembly Plant past December 2019.鈥

鈥淏ased 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,鈥 the union鈥檚 statement said.

鈥淯nifor is scheduled to hold a discussion with General Motors tomorrow and will provide further comment following the meeting,鈥 the union added.

Federal Conservative Leader Andrew Scheer tweeted that his 鈥渉eart goes out to all those affected by this devastating decision.鈥

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鈥橳oole, who represents the riding of Durham, said on Twitter that, 鈥渇rom the calls I have been making tonight, it appears these reports about an end to vehicle assembly in Oshawa are true.鈥

鈥淭his is devastating news to families in Oshawa, the Durham region and all of Ontario,鈥 O鈥橳oole added. 鈥淕rowing 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.鈥

Oshawa MPP Jennifer French, a New Democrat, told CP24 that 鈥渋f the news is true,鈥 then Oshawa is 鈥渂racing ourselves for a fight.鈥

鈥淟et鈥檚 be real here,鈥 French said. 鈥淕M didn鈥檛 build Oshawa, Oshawa built GM.鈥

More than 100 years of history

GM鈥檚 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鈥檚 Miranda Anthistle that he鈥檚 hoping the plant closure is 鈥渏ust a rumour鈥 because GM is a 鈥渉uge economic engine to the community.鈥

鈥淢y entire family has worked at General Motors,鈥 said Henry. 鈥淢y 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.鈥

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

鈥淚t鈥檚 very different now than when I was growing up, when everyone you knew was working in the plant,鈥 he said.

鈥淲e鈥檝e diversified and we have a lot of other things going on,鈥 he added. 鈥淏ut the car industry is still a big part of our community.鈥

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