Firefighters rushed to a Fulton Hogan yard in Hamilton overnight, to deal with a blaze.
Nine crews were called to the Higgins Road complex at about half past two this morning.
Fire communications shift manager Daniel Nicholson says when crews arrived they found three truck and trailer units alight, and foam had to be used to extinguish the blaze.
It was put out shortly before six this morning. No one was injured.
Police are now investigating.