FORT KENT – Officials with the State Fire Marshal’s Office combed through the rubble at an East Main Street site Friday afternoon in the aftermath of a blaze that extensively damaged a building that houses some Northern Maine Medical Center offices and the Fort Kent Ambulance Service.

Construction workers discovered the fire at the facility at about 2:45 p.m. Thursday, according to Carol Anne Dube, spokeswoman for Northern Maine Medical Center.

Dube said Friday that the initial damage estimate of $500,000 was far too conservative.

“The second floor of the building was extensively damaged, and what the fire did not get smoke and water did,” she said. “We expect the damage estimates to be even higher than we initially thought, but we don’t have a final number yet because we are waiting for the extent of the damage to be determined.”

The building, which was being renovated for additional offices, houses the hospital’s Wellness Center, offices of the St. John Valley Partnership, Fort Kent Ambulance and Visiting Nurses of Aroostook.

The building is owned by James Pelletier. It was evacuated without incident.

Fort Kent Fire Chief David Pelletier said Friday that the investigators were still working to determine what sparked the blaze.

Firefighters were at the scene Thursday for more than five hours.

Some of the offices that were damaged were relocated Friday to an apartment building in town, according to Dube. The cardiac rehabilitation program will be shut down for at least a week, she added, until officials decide how best to meet the needs of the people who use that service.

The facility will undergo reconstruction, Dube pledged Friday, but a timeline and location have yet to be determined.