FORT FAIRFIELD – One of two workers injured Tuesday in an explosion at the Boralex Fort Fairfield Inc. power plant remained in the hospital Friday.

Rick Thompson, 47, of Caribou was reported in serious but stable condition at a Boston hospital, according to Jean Roy, general manager for power generation for Quebec-based Boralex. He did not know the name of the hospital. Thompson reportedly was burned over more than half of his body.

The other man, Scott Haggerty, 35, of Presque Isle, returned to work Friday, Roy said.

The men were injured about 5:15 p.m. Tuesday while doing maintenance during a routine shutdown at the biomass generating plant.

They were working on a piece of equipment when there was a sudden burst of heat or small explosion, Roy said.

The men were taken by ambulance to The Aroostook Medical Center in Presque Isle and later transferred by LifeFlight helicopter and Crown Air Ambulance airplane to Maine Medical Center in Portland.

Thompson later was transferred to Boston.

According to Roy, the cause of the explosion was not known. He said the company had hired a third party to investigate the accident.

He said the Occupational Safety and Health Administration had not been notified of the accident because it was not necessary to do so.

The supervisor at the OSHA office in Bangor was not available Friday, but a woman who answered the phone said they did not become aware of the accident until they read about it in Friday’s paper.