The cause of a massive fire that destroyed a wood processing plant in Northbridge cannot be determined, officials announced Thursday.

While there was no sign of arson, the extent of the fire, and the need to use heavy equipment to fight, makes it impossible to rule out several accidental causes, state and local officials said in a statement.

“The fire will remain officially undetermined,” the statement said.

Some of these possible causes include machinery failure or the incorrect disposal of smoking materials.

The six-alarm blaze, which was reported at 8:15 p.m. caused an estimated $1.3 million in damages at the plant owned by West End Firewood, the statement said.


The fire consumed seven buildings, several forklifts and logging trucks, and 700 cords of wood.

Stephanie Purifoy can be reached at stephanie.purifoy@globe.com