Combine deer drives with people shooting rifles or buckshot and practically no visibility through the brush and this is not as rare an occurrence as it should be. If you have never hunted deer in some parts of the east and south where this is common (though I am not saying this is the only style) it's hard to compare it even remotely to western deer hunting. But the analogy of pushing pheasants or rabbits is close. Quick shots at fleeing game at close quarters, with people around. Can be dangerous for people in the drive, and dangerous for people not involved in the drive... these are usually coordinated amongst a small group, but on public land there's little chance of accounting for who else might be around. It's not always even drives, just the terrain, visibility, and close proximity in general of eastern woods. It can happen one on one.
So tragic hearing about the young kid, above all.