The United Auto Workers union went on strike at three plants owned by the Big Three automakers – General Motors, Ford and Stellantis – after the two sides did not reach a new labor deal on Thursday night.

UAW President Shawn Fain announced the historic strike after months of failed negotiations for a four-year contract with autoworkers.

"Tonight for the first time in our history we will strike all three of the big three at once," Fain said in a Facebook live announcement.

Fain called upon the workers at a GM plant in Wentzville, Missouri; a Stellantis plant in Toledo, Ohio; and a Ford plant in Wayne, Michigan, to "stand up" and walk out on strike tonight at midnight in what he called a "stand-up strike."

Plants that were not called upon to strike will work without a contract, Fain said.

LOOMING UAW STRIKE COULD COST US ECONOMY MORE THAN $5B IN JUST 10 DAYS 

Fain says this strategy will keep the automotive corporations guessing, with leadership determining further strikes. 

UAW workers will hold a rally on Friday at 4 p.m. ET.

The main point of contention between the two sides is higher pay, with Fain saying the union is seeking a more than 40% general pay raise for rank-and-file members over four years.

FORD, GM, STELLANTIS DEALERSHIP BRACE FOR POTENTIAL UAW STRIKE

Full-time assembly plant workers at Ford and GM earn $32.32 an hour, while part-timers currently make about $17 an hour. Full-time employees at Stellantis earn $31.77 an hour, and part-time workers earn close to $16 an hour.

The union is also pushing for making all temporary workers at the automakers permanent, cost-of-living adjustments, increases in pension benefits for current retirees and restoring pensions for new hires, among other benefits. 

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Fain has called the demands the "most audacious and ambitious list of proposals they've seen in decades." 

FOX Business' Megan Henney contributed to this report.