at 5:16 a.m., one minute after floyd's entrance into the store, a worker hiding there is able to place a frantic 911 call. >> 911 emergency. >> we need help, please. >> what kind of help? >> this is albertson's. we're on sahara and valley view. there's a guy with a gunshot in here. oh, my god. he's running all over the store. >> the police are on their way. but zack is still trapped in the store with a killer. some instinct tells him not to move, that it isn't over yet. and it isn't. floyd is coming back. here he's walking up the aisle in the produce department. he's almost out of frame when suddenly, he doubles back toward zack. >> he walks over me and he just kind of leans over me to make sure, you know. i was just lying there, closing my eyes. i didn't exactly know where he was. i did kind of hear him come back. so i was just laying there. he bends over me and walks looking for more people. >> give us a code red. units arrived. >> by 5:19, the police have arrived.