 About fifty people were on the top wooden balcony at the time of the collapse . According to one witness , the sound of splintering wood was heard immediately before the collapse , which occurred shortly after midnight local time . The collapse started on the third floor , pulling down other balconies below . The first , second , and third floor balconies all collapsed into the basement below , carrying a total of approximately one hundred people among them . Several people were also trapped in a basement stairwell . Survivors helped to pull victims out from under the debris of the balconies , and rescue workers had to use chainsaws to free others . One of the survivors was a nurse , and had started a rescue effort before the emergency services arrived . The Chicago Fire Department supplied the main rescue effort . Eleven people were killed in the collapse , with two more subsequently dying while hospitalized ; fifty @-@ seven people were injured . 
