They were not intentionally killed, the security forces were untrained in the use of rubber bullets and shot them directly at protestors rather than having them ricochet off the ground.

That statement reflects a basic misunderstanding of small arms. If you shoot at someone, regardless of whether you're using less-than-lethal ammunition, death or serious injury is always possible. This was absolutely intentional by the soldiers and those who gave the orders. Don't try to claim it was some kind of accident, regardless of training or lack thereof.

I really love the rising justification as of late of "they didn't know" for reckless manslaughter.

They're called "less lethal" for a reason. It's not a paintball that splatters on impact (and even then, those can also harm). Even a properly shot rubber bullet carries injury risk if you're too close. What's all that police training for?

if you point a gun at someone and pull the trigger, then they die from injuries caused by the shot you fired, you killed them. what goes on in your little secret heart between you and jesus might matter to you, but to the real world everyone else lives in you killed them. whether you meant to shoot them in a non-killing way is irrelevant, doubly so if you never learned how to but decided you were qualified to do it anyway.

No difference. Not knowing does not excuse responsibility. Should have figured it out after first death.