It turns out that it was two cars shooting at each other outside the stadium, but four bystanders got hit.
I was leaving the game as it happened. Luckily I left through the CF gate, as opposed to 3rd base. But once word spread, it was absolutely wild, people running in every direction.
The truth is that it shows how legitimately afraid people are that they can be caught up in one of these events. You could've had more injuries from the panic than from the actual shooting. The $15/hr Nationals employees don't know how to control a situation like that. Had it actually been an active shooter, holy crap what a stampede you would have on your hands.