SANFORD, Maine (NEWS CENTER) -- The Maine State Fire Marshal Office reported Friday that a fire at a mill on River Street on Thursday was intentionally set.

Sergeant Ken Grimes could not say what started the fire, but believes it was "ordinary combustibles," and say no accelerant was used.

Sergeant Grimes said they do not have anyone in custody yet and they are still investigating.

Grimes said the mill was vacant. It is on the same property where a group of boys set fire to a different section of the mill over the summer.