Stop & Shop workers walked out of the job on Thursday as part of a strike carried out as a result of delayed contract negotiations.

The supermarket chain — which is headquartered in Quincy, Mass. — experienced a worker strike on Thursday as tens of thousands of employees walked out. These include workers in Massachusetts, Connecticut and Rhode Island locations.

The Stop & Shop employees are being represented by the United Food & Commercial Workers union–some of these workers were picketing outside the stores. “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,” the leaders of five locals said in an emailed statement.

“They have earned and deserve a good job that allows them to do what they do best: provide the very best customer service for New England communities,” they added. There are more than 31,000 employees who were encouraged to join in the strike by authorized union leaders.

Stop & Shop has roughly 415 stores across the Northeast, with the strike affecting about 240 stores in the aforementioned three New England states. Store managers were reportedly able to keep stores in operation by allowing customers to use self-checkout lanes.

The chain announced on its website that it was disappointed with the strike as negotiations are ongoing with the help of federal mediators.