Nearly 4,500 National Grid customers in Andover were without power Sunday night, according to an outage map on the company's Web site.
The outages, which apparently began in Tewksbury and spread into sections of Wilmington and Andover, were triggered by a transformer fire on Route 38 near the Knights of Columbus in Tewksbury.
Power went out just after 8 p.m.
Tewksbury Firefighters and National Grid crews responded to the scene.
There is no immediate word on when power will be restored.