Over 3,600 UAW workers at Mack Trucks, a subsidiary of AB Volvo (VOLV-B.ST), went on strike at 11:59 p.m. Saturday. The strike affects five Mack Trucks plants located in Allentown and Middletown, Pennsylvania; Hagerstown and Baltimore, Maryland; and Jacksonville, Florida.

The workers are fighting for “fair pay, benefits and job protections,” according to a statement from the UAW.

Unresolved issues for the union workers revolve around “wage increases, job security, COLA, wage progression, skilled trades, shift premium, holiday schedules, work schedules, health and safety, seniority, pension, 401(k), healthcare and prescription drug coverage, overtime, subcontracting, and temporary/supplemental workers.”

“UAW members get up every day and put in long, hard hours of work from designing to building Mack trucks,” Ray Curry, secretary-treasurer of the UAW and director of the Heavy Truck Department said in a statement. “UAW members carry on their shoulders the profits of Mack and they are simply asking for dignity, fair pay and job protections.”

Mack Trucks responded to the strike by issuing a statement from President Martin Weissburg that read, Mack Trucks is "surprised and disappointed that the UAW decided to strike, rather than to allow our employees to keep building trucks and engines while the parties continued to negotiate.

“The positive working relationship between local UAW leadership and management at our facilities was clearly in evidence throughout the negotiations, and progress was being made,” he added.

Mack Trucks produces heavy trucks and engines for the North American market. The company cited that it invested more than $400 million in its plants and logistics network over the last 10 years and created more than 500 jobs in the U.S. at its factories.

“We are committed to the collective bargaining process, and remain confident that we will be able to arrive at an agreement that provides a competitive wage and benefit package for our employees and families, and helps to ensure the company’s competitiveness,” Weissburg said.

The Mack Truck worker strike joins more than 46,000 General Motors employees that went on strike on Sept. 16. GM has laid off workers at plants in Mexico and Canada as a result of the UAW strike.

Shares of AB Volvo stock were up 0.18 percent as of 11:28 a.m. ET on Monday.