Unfriendly chinese people?

today i saw a young chinese man laying on the floor, in pain.. a lot of chinese people kept passing him and stoppping by him and looking at him and walking away, they did not HELP him.. atleast 15 chinese people came up to him and walked right away, until one american man held an umbrella over his head and another american dialed the emergency phone number. is there a reason why the chinese people (people of his own) didnt help him???? i was so surprised!