NEWPORT — Five city restaurants affected by the natural gas outage filed a lawsuit against National Grid and Enbridge in Superior Court on Thursday.

Sardella’s Italian Restaurant, Stoneacre Brasserie, Stoneacre Tapas, O’Brien’s Pub, and Scales & Shells are the plaintiffs represented by attorneys Robert Karns and John Fulweiler.

The plaintiffs seek compensation and damages to “make them whole again” and punitive damages.

The complaint alleges that negligence caused the “Newport Gas Crisis,” among other factors, including “National Grid’s six-month lockout of 1,200 of its union employees, National Grid’s reliance on contract labor and the Defendants’ failure to analyze, invest, renew and maintain the infrastructure relied upon to supply and distribute natural gas to the City of Newport.”

The complaint is not a class-action lawsuit, Karns and Fulweiler said in a statement. “Plaintiffs will be added to this lawsuit when our offices are contacted,” the statement said.

This is the third known lawsuit filed in recent days against National Grid and Enbridge, which is the company that owns and operates a pipeline in Massachusetts that supplies National Grid.

Attorney Brian Cunha filed a class-action lawsuit representing eight Newport residents and a separate class-action lawsuit representing BHK Realty Inc. at 536 Thames St. and The Bodhi Spa at 654 Thames St.

There were almost 6,500 customers in Newport and another 340 in Middletown who lost gas service because of the outage and a subsequent shutdown that started Jan. 21. Service was restored to most affected customers by Jan. 28.

Enbridge acknowledged an “equipment malfunction” was a factor in the outage, The Providence Journal reported.

The latest lawsuit said National Grid locked out about 1,200 of its union workers in Massachusetts around June 2018 because of a contract dispute. The utility continues to rely on contract workers to fulfill the responsibilities of the locked-out employees, the complaint says. It emphasizes that Massachusetts is where “the alleged pressurization issue associated with the Newport Gas Crisis occurred.”

A National Grid spokesman did not immediately respond to an email seeking comment.