At least 99 people are still missing after a 136-unit building came crashing down. The question of what caused this tragedy remains unanswered. WATCH NIGHTLINE EPISODES: https://abc.go.com/shows/nightline ALSO AVAILABLE ON HULU: https://hulu.tv/2wSmSrZ #Nightline #Florida #Miami #Dade #MayorCharlesBurkett #BuildingCollapse #FireChiefStevenMcGill #PeterDyga #Rescue