Thousands of customers across northeast Massachusetts from Tewksbury to Rockport have been without Internet and phone service since early Monday after a mattress being used by a homeless man caught fire adjacent to Verizon’s copper and fiber optic cables on a bridge that crosses the Merrimack River.

”Your communications services may have been interrupted due to a fire in Lawrence that damaged a major cable providing service to your community,” Verizon’s dispatch manager Donna Powers wrote in letters sent to officials in the affected communities.

The outages are impacting communities including Gloucester, Manchester, Rockport, Essex, Littleton, Lawrence, Andover, North Andover and Tewksbury, and points in-between.

With high-capacity fiber circuits out of action, regional calls and certain Internet services were disrupted. Verizon is giving priority to restoring network operational and surveillance circuits, high-capacity fiber backbone circuits, and 911.

Verizon will not give a time frame when it expects to fully restore service, although the company indicated it is now rotating crews continuously to restore service to individual homes and businesses in the Lawrence and North Andover areas.

Lawrence Fire Chief Jack Bergeron said the problem started with a lit cigarette disposed on a vagrant’s mattress, which was on fire by the time firefighters arrived on scene. The mattress was on top of conduits that contained the copper and fiber cables, despite signs marked “danger” and “high-voltage.”

With no redundant backup facilities, a major outage can leave customers without service for days until repairs are completed.