Excerpts from the ChicagoTribune.com:

Two neighboring houses on Naperville’s far northeast side were badly damaged by fire Wednesday night.

The fire was spotted about 6:10 p.m. in the attached garage of a two-story frame house in the 500 block of Springhill Circle, and then spread to a two-story frame house next door.

The first house was fully involved by the time firefighters arrived. Forty-five firefighters and 19 vehicles were needed to bring the fire under control in 45 minutes.

Investigators determined Thursday the fire was accidental in nature, however the intensity of the blaze and the magnitude of the damage means the fire’s source will likely never be learned. 

thanks Dan