Officials say firefighters found six manhole covers had blown off their bases early Monday. Fire shot up from the ground. At least two businesses had to evacuate.
National Grid says it responded to several manholes in the Boston suburb. No injuries were reported.
The utility told The Enterprise that electrical service for its customers wasn't affected. The company is looking into what caused the explosions and was repairing a manhole. The company says its underground equipment is now functioning properly.
Flames also erupted from underground in July, hurtling manhole covers into the air.
National Grid says those explosions were caused by a faulty underground electrical cable, which can lead to the accumulation of combustible gas.