After seeing more video, I might not have been initially correct.
It appears the black man with the gun was initially stabbed by what looks to be a Latino man. After being stabbed, the black guy pulls out his own gun, is disarmed by the Latino man, who then shoots him.
Colosseum death match by the Rainbow Coalition on NYC's subways.
Thanks, I have not seen any video of the incident.
IMHO the world is going mad.