County firefighters are investigating an early morning suspicious fire in the Desert Heights neighborhood of Twentynine Palms. Joshua Tree, Yucca Mesa, and Combat Center firefighters were called to the 1000 block of Friendship Avenue at 3:15 this morning for a fire in a big rig trailer filled with books, clothing, household supplies, and other items. County Fire Battalion Chief Scott Tuttle said crews were on scene for about 2 ½ hours putting out the blaze and mopping up. The residents were not at home at the time of blaze. There were no injuries.