Northern Light Health and Anthem Blue Cross Blue Shield announced late Wednesday night that they have reached an agreement on a multiyear contract to keep health coverage in-network for about 30,000 Mainers.

In a joint statement, the hospital system and insurance company said the contract — its exact length was not immediately clear — would be retroactive to Nov. 1. A contract between the two parties for non-hospital services — including physicians, specialists and walk-in clinics — ended Oct. 31.

“This new agreement allows our patients to continue receiving high-quality care from the providers they know and trust. Northern Light Health has long been a reliable source of care in Maine and will remain that for generations to come,” Northern Light President and CEO R. Guy Hudson said in a written statement. “Throughout the negotiations we kept our patients’ needs at the forefront, and we will continue to advocate for them and the communities we serve.”

“Anthem is deeply committed to ensuring Mainers have broad access to the care they need at prices they can afford,” Anthem President Denise McDonough said in a statement. “We’re pleased to have reached an agreement that keeps Northern Light Health in-network for our members and helps us continue delivering on our promise to improve lives and strengthen the health of our Maine communities.”

The two sides had been entangled in negotiations on a deal — which included a formal mediation process that began in August — for several months.

With the contract lapsed as of Oct. 1, as talks were still ongoing, Anthem patients in Maine were considered out-of-network for a few hours until a one-month contract extension was signed.

Northern Light operates Eastern Maine Medical Center in Bangor, Mercy Hospital in Portland, and a network of primary care and specialist services in much of northern and central Maine.

About 30,000 Anthem enrollees are Northern Light patients, including state employees and some nurses and firefighters.