How they are killed,- chemical, bomb, bullet, knife, axe, starvation or disease.
It's been going on for years,the poor seem to always be at the blunt end of it.Those responsible are the politicos, it's no good throwing cruise missiles at them, it won't help, it will just be another expensive form of killing more innocents. Responsibility for all the atrocities, lies with the leaders.
Stop supporting the arms companies and just take care of the evil leaders, it can't be that hard with technology being at it's current level.
Start with Assad, if not possible to assasinate him, offer him a way out, give him a plane with as much beer as he can carry, those of his harem who want to stay with him and amnesty(then shoot him down as he takes off).