>> reporter: carol hoffman was working out in the basement. >> i don't know if this is real. >> skyforce10 was high above. mike wallace knew the reality. he could see the flames and feel the heat. he took cell phone footage and watched the fire grow in size and alarm. he had seen contractors using a blow torch on the roof. >> they were torching down rubber on there and i guess it slipped up under the roofing. >> reporter: hoffman climbed the steps to the main level to see if she and others needed to get out. >> by the time i got to the top of the steps i could see people running out in bathing suits. >> reporter: fearing they could become trapped or worse she shouted to a man at the bottom of the steps. >> i screamed to him, turn around and screamed to everybody to get out. >> reporter: on the massive 40,000 square foot center main level marissa brooks and official physical therapy employees also scrambled but say they knew what to do. >> it went off and instinctively we all thought it was a drill but once we realized it wasn't we were very efficient about getting everybody out. >> there w