Typical Detroit. Bump into someone on a crowded bus, get murdered.
The same thing happened when I was in high school. Our school was horrendously overcrowded, so bumping was inevitable. One day a guy going up the stairs collided with a guy going downstairs. Downstairs took exception to being "disrespected", shot upstairs in the chest.
Upstairs died. He might have lived, but the idiots in the head office decided to move him away from the stairwell, when he really started to bleed out in earnest.