They say a discarded cigarette on the balcony lit up the Brookstone Apartments in the 6500 block of Brookstone Lane.
The windy conditions are believed to have accelerated the fire and quickly spread it to adjoining apartments.
At last report, no charges have been filed.
The heat from the fire was so intense that it melted vinyl siding on a building next door.
Three end apartments were gutted or damaged. Three others suffered smoke and water damage.