A fire in a bottom unit of a 6-unit apartment complex caused severe damage to one apartment, moderate to one other and smoke damage to two more.The cause of the fire, shortly before 1 p.m. Monday, at 3429 Airport Road is unknown at this time but the fire started at the rear of the first-floor apartment. The flames then spread up the outside wall and went into the attic, Carson City Fire Chief Stacey Giomi said.The first floor apartment suffered extensive damage, the apartment above it suffered moderate damage from both smoke and flames and the other apartments suffered smoke …