NEWPORT — The Newport Fire Department has yet to determine the cause of the fire at Newport Structures LLC after firefighters from six area departments spent eight hours battling the blaze on Tuesday.

Newport Structures LLC builds and delivers portable storage buildings.

The Newport Fire Department received a 911 call at 11 a.m. Tuesday and arrived at the commercial building on Grogin Avenue around 11:08 a.m., Fire Chief Jeff Chretien said Wednesday. No injuries were reported, and the cause of the fire has not been determined.

The situation was unique because the department hasn’t dealt with many large commercial building fires that have spread through the ceilings and walls so extensively, Chretien said. He noted one other place, Vic Firth Co., which manufactures music drumsticks and mallets, that firefighters have responded to over the years.

“We had a lot of difficulty because it was a metal building on the outside,” he said. “It had metal siding and a metal roof. And on the inside, in their work space, it had metal walls and ceilings. The fire was between the ceiling and the roof.”

The fire traveled about 100 feet across the building, Chretien said. Newport Structures LLC does not have a sprinkler system.

Firefighters had to use an excavator to remove five dormers from the building so they could get water into the roof.

Crews from other fire departments — Detroit, Hermon, Pittsfield, Plymouth and St. Albans — also responded to the fire call.

When firefighters arrived, about 20 Newport Structures LLC employees had evacuated and were standing outside, Chretien said. Smoke was coming from the eaves of the building.

The owner of the building stayed until the fire was fully extinguished, the chief said. He sent employees home at about 3 or 4 p.m.

The fire caused too much damage for employees to return and continue working inside safely. An engineer will likely have to inspect the building, Chretien said.

Newport Structures LLC posted on its Facebook page that “due to unforeseen circumstances,” the office will be closed for the rest of the week, but the staff will be available by phone or through Facebook Messenger.

The business declined to comment on Wednesday.