The Sparks Fire Department responded to a report of a dumpster fire threatening a structure in the 1400 block of Scheels Drive in Sparks Tuesday. Investigators say arson is suspected. The fire was started behind the Forever 21 store. Fire crews found exterior damage to a building. The Adidas store nearby was evacuated but it was reopened a short time later. The fire was reported shortly before 7:00 Tuesday evening.