This from Steve Redick:

This was about 0200 Saturday morning. A large warehouse stacked floor to ceiling with junky combustibles. The fire was in an outside rubbish/storage area beneath an overhang. For a bit it looked like the fire had gotten a hold in the building. Bar joist truss construction and initial heavy smoke and excessive stock inside made for a defensive operation for most of the fire. The MVU was used to clear the building once the fire was contained. This could have been a real dandy but fortunately everything worked out well.
Steve
 
All the images and video can be seen here:
smoke from warehouse fire

Steve Redick photo

Chicago fire truck at work

Steve Redick photo

Chicago fire truck at work

Steve Redick photo

Chicago firefighters at work

Steve Redick photo

Chicago firefighters at work

Steve Redick photo

Chicago FD Mobile Ventilation Unit 6-2-3

Steve Redick photo