Two employees of NSTAR were injured this afternoon as the result of some type of explosion at the utility's Charlestown facility, according to Boston police.
One worker sustained smoke inhalation and the second was severely burned, said Office Eddy Chrispin, a department spokesman. Both were transported to Massachusetts General Hospital where their conditions were not known.
NSTAR spokesman Michael Durand said the workers were performing routine maintenance in a substation attached to the Mystic power plant in Everett when the incident took place around 1:30 p.m.
For reasons that are under investigation, high voltage electricity escaped from insulated wiring causing a "flash incident'' that injured the workers, he said.
Durand said the injuries were not life threatening.
Police said the incident is under investigation by the federal Occupational Safety and Health Administration.
The facility straddles Boston and Everett and the Everett fire department is also investigating.
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