At 0403 this morning, crews from Chelan Fire & Rescue were dispatched to a reported commercial fire alarm activation at 302 E. Woodin Ave.  Manager on site reported light smoke inside the occupancy and fire crews immediately upgraded the call to a commercial fire.  Flames and heavy smoke were reported on the roof and fire crews initiated fire attack with aerial (ladder truck) master stream.  Crews attempted to enter the building but pulled back due to partial collapse of the ceiling and moved into defensive fire operations.  A third alarm was called bringing additional resources from LCCH EMS, Manson, Orondo, and Entiat to assist with fire suppression operations.  A total of 33 fire personnel and 14 apparatus were used to bring the fire under control at 0531 with no reported injuries.  Cause of the fire is currently under investigation.