General Motors Corp workers at plants in Michigan, Ohio and Kansas began walking off the job and organizing pickets as a national strike against the automaker began on Monday.

We're on strike. It's too late to call us back now, United Auto Workers Local President Chris Tiny Sherwood told Reuters as a union-imposed strike deadline passed at 11 a.m. EDT.

UAW local leaders had been told to have 73,000 union-represented GM factory workers begin walking off the job on Monday morning unless they were told by the UAW's negotiating team that an impasse in 10-week-old contract talks had been broken.

At a GM plant in Bay City, Michigan, union workers began to picket in front of the gate with signs reading UAW on Strike.

The strike is the first against GM since 1998 and marks the first time since 1976 that the UAW called a national strike in the midst of contract talks with one of the U.S. automakers.

UAW Local 22 President George McGregor said he hoped the strike would force both sides to reach a quick agreement.

I don't know what the hang-ups are, but I know that there are some hang-ups, McGregor said of the negotiations on a deal on wages and benefits to replace the contract that expired September 14. I hope they can settle today or tomorrow.

He added: Everyone's hurt by a strike. Everyone pays the price for a strike.

Representatives of GM and the UAW could not be reached for immediate comment.

(Additional reporting by Nick Carey)