Both Jennifer and Tina were vomiting. During the time when they fought those Warriors and even killed them, both of them did not feel anything.
But sometime later, both of them began to feel very guilty, and at the same time, both of them started vomiting.
This would be the first time they kill someone. Sam, at this time, did not say anything to them and gave them the time to stabilize their condition.
Naturally, he knows that both of his students will face this kind of situation. But this is also a lesson that they need to learn.
If you were wondering if they didn't have to kill those people, then you are wrong.
First of all, you need to understand that this is not your peaceful Earth. Everything is different here and you need to stay careful all the time.
People like them will always try to take advantage of you and even try to kill you for their own benefit.
