People getting hit and hurt is always possible when others are randomly chucking objects in their direction.
An 18 year old kid who has grown up watching fans throw crap onto the field whenever something doesn't go their way in a game likely never even stopped to think about what he was doing. And that's why it has to stop. Start issuing warnings pre-game and telling people, "These are the consequences if we catch you throwing anything onto the field. You will be ushered out of the stadium. You will be banned for the season. You could face possible legal citations." Or whatever else it's going to take, but this kind of crap has to stop.
It's a nation wide problem.