among the survivors were three new york police officers: bill beaury, mark demarco, and detective danthey were inside the world trade center complex when the towers came down. we partnered with retro report, a non-profit news organization that uses history to inform the present, to tell their story. >> a plane has just crashed int the world trade center here in new york city. >> at 8:46 a.m., american airlines flight 11 crashed into the world trade center north tower, building one. it was one of four planes hijacked by 18 al qaeda terrorists that day. at first, it seemed a tragic accident-- an airplane off course. >> as i'm watching this trying to figure out, do i have to go to work? the second plane hit, and i saw it on tv. and that was it. >> al i seen is this huge fireball coming out of tower two, out of the south tower. and for a second i didn't know what it was. i thought maybe just the building blew up. >> i ran downstairs, and i'm looking southand both towers are on fire. and it was stunning. >> sreenivasan: with the second catastrophic strike, it became clear that the country