Mesa Fire and Medical Department crews were called out to battle a first-alarm fire at the Walmart Supercenter near Dobson Road and Rio Salado Parkway at Mesa Riverview on Thursday. The blaze broke out in the garden area of the store. When crews arrived, they found heavy smoke in the area. Fire officials say several pallets of merchandise had caught fire. Photos from one of our viewers showed a plume of gray smoke rising from the store. Crews quickly put out the fire. The store ended up with a large amount of smoke damage in the retail area. No one was hurt. The cause of the fire is under investigation.