oakland, california. it's just after 2:00 in the morning when a bay area rapid transit train, known as b.a.r.t., pulls into the fruitvale station and the doors open. a b.a.r.t. police officer tells five men who step off the train to wait on the platform. two of them defy the instruction and get back on the train. >> out of nowhere, i heard, get off the train, get off the train. and some curse words after that. >> like many of the train passengers, tommy cross is on his way home from seeing the new year's eve fireworks show in san francisco. when he sees the officer entering the train car. >> i thought he was coming for me for a second, but he went right past me. and grabbed the young man who just walked on the train. >> the b.a.r.t. police officer, tony peroni, is responding to a report of a fight on the train that the conductor called in. >> the lead car, no weapons, all black clothing.