LINCOLN, Maine — Firefighters responding to a fire reported at a Main Street wood-shavings mill Friday were assisted by a sprinkler system that held down the flames for hours, officials said.

The fire had been burning for perhaps as long as nine hours before firefighters were called to LMJ Enterprises, 431 Main St., at about 6 a.m. The building’s fire alarm system, however, appears to not have activated, a mystery in a fire that does not appear to have suspicious origins, according to Dan Summers, Lincoln’s public safety director.

“We will know more once the investigators from the fire marshal’s office get there and start doing their more in-depth investigation,” Summers said Friday.

Firefighters from Burlington, Lowell and Mattawamkeag fought the fire with Lincoln crews, and Howland firefighters manned Lincoln’s station for the duration of the emergency. No injuries were reported, Summers said, but extensive heat and water damage occurred to the warehouse-sized building, one of six on the campus of LMJ Enterprises and the former Haskell Lumber Inc. hardware store.

The only visible evidence of the fire externally was smoke pouring from the top of the angled roof. Besides mounting an interior attack on the fire, firefighters used a ladder truck and a freestanding ladder to cut into the southeastern side of the building to get at flames, which showed briefly.

Summers estimated the fire might have done as much as $200,000 in damage to the building, but he conceded this figure was “an uneducated guess.”

Firefighters hope to use water meter readings to determine for exactly how long the sprinkler system was engaged. A great deal of water was in the building when the first firefighters arrived, Summers said.

Owned by longtime Lincoln businessman Lee Haskell, LMJ Enterprises makes wood shavings for livestock bedding and other uses for sale through a nationwide retailer and farm supply store, company officials have said.

Haskell could not be reached for comment by noon Friday.

Firefighters did a very good job limiting the damage done to the building, Summers said.

Another fire was reported at the site April 28. The mill’s screening equipment and some other machinery at the east end of the main building were destroyed. The screening equipment separates shavings from sawdust.

Friday’s fire was the second reported in Lincoln this month. A West Broadway flower shop was destroyed Jan. 16. An adjacent pool and dance hall remains closed, though the owners of both places have said they plan to reopen.