. >> reporter: laura o'brien says after surviving a 43-foot free fall she could hear the screams, o'briennd her roommate nantz write seriously injured, albert su was dead. a year and a half later there are still in requirements for fire escapes to be inspect in philadelphia. remnants of the police tape in the alley on between the second and locust mark spot where one life was lost and two others narrowly survived a devastating collapse on the night of january 12th, 2014. >> it was like the loudest rumbling, crash i had ever heard. >> reporter: it was laura o'brien's first time standing on the makeshift balance conn which two roommates. during a party for a friend's birth the day. but the celebration quickly turned tragic. >> my arms went over my head, i went straight down so quickly. >> reporter: o'brien survived the fall but broke her back. when another roommate was seriously injured. >> i could hear my roommate nancy yelling. >> reporter: albert su was not the so lucky. >> first thing i thought was that is not possible. >> reporter: his older brother men, spoke with us through tears. >>