Thousands of Stop & Shop workers walked out in a strike that forced stores to close for hours

Stop & Shop workers went on strike on Thursday, protesting cuts on healthcare and pension benefits.

31,000 employees of the Ahold Delhaize-owned regional grocery chain who are members of the United Food & Commercial Workers (UFCW) walked out of their stores in Massachusetts, Rhode Island, and Connecticut on Thursday afternoon.

Workers left stores around 1 p.m., with many picketing outside of the stores. Many stores - lacking employees - closed for a portion of the afternoon. The majority of stores reopened on Friday morning with temporary replacement workers as the strike continues, a Stop & Shop representative told Business Insider.

"Given that negotiations with assistance of the federal mediators are continuing, we are disappointed that the UFCW chose to order a work stoppage in an attempt to disrupt service at our stores," the retailer said in a statement. "Stop & Shop has contingency plans in place to minimize disruption."

According to the UFCW, Stop & Shop's proposed contract would increase healthcare premiums by hundreds of dollars and reduce monthly pension benefits for many newly hired employees.

"Instead of a contract that recognizes the value and hard work that our members provide every day, Stop & Shop has only proposed drastic and unreasonable cuts to health care benefits and take home pay, while replacing real customer service with more serve-yourself checkout machines," representatives of the local UFCW unions said in a statement.

Some shoppers posted about their experience at Stop & Shop as the strike kicked off on Thursday afternoon on social media.

"Stop and Shop called their strike when I was in the middle of shopping ... so I ditched my cart and left. Take care of your people and you'll get my money," one person tweeted.

"Just walked into Stop and Shop and the PA system goes 'Everybody out we are officially on strike' and all the employees legit just left. FIGHT THE POWER BABY," tweeted another.

The UFCW and Stop & Shop reached a stalemate while negotiating a new contract in recent months, with employees working without a contract since late February.

"The men and women who make Stop & Shop a success have earned and deserve affordable health care, a good wage, and the ability to retire with dignity," local unions said in a statement.

Stop & Shop said in a statement that its employees have some of the highest wages and best benefits in the grocery industry. The company also said it needed to cut costs, as the majority of rival grocery chains in the New England area, such as Walmart, Costco, and Whole Foods, are not unionized and have lower labor costs.

"Stop & Shop is the only large fully-unionized food retailer left in New England," the company said in a statement on its website. "Our labor costs are having a major impact on the company's ability to compete in a fundamentally changing market."

A number of politicians spoke out in support of UFCW and Stop & Shop workers on Thursday.

".@Stopandshop, a multibillion-dollar company, wants to drastically cut health care for 31,000 workers. I stand with @UFCW workers in their fight to protect health care and workers' rights," Sen. Bernie Sanders tweeted.

Sen. Elizabeth Warren tweeted: "31k New England @StopandShop workers just went on strike for a contract that provides fair wages, good benefits, & a secure retirement. I stand in solidarity with @UFCW for these hard-working families to be treated with the dignity & respect they deserve."