Firefighters thought they were responding to a house fire in Joshua Tree Tuesday evening, but it turned out it was just a vegetation fire. Battalion Chief Donnie Viloria said the fire was called in at 6 p.m. last night by a neighbor near Hilltop Drive and Sunset Road who saw ornamental pampas grass on fire next to a home’s back patio, and thought the fire was starting to burn the back porch. The pampas grass was burning in a semicircle around the patio, but the house was not on fire. Joshua Tree firefighters quickly put out the blaze. Viloria said the cause of the fire is under investigation.