Instantly one of them got cut into pieces while the other one lost his leg. Sam did not kill him because he wanted to know why they came here and many other things. That other one didn't even realize when he got killed. That person who just lost his leg, at first did not realize that. But then his body suddenly fell into the ground, only then he realized something happened to his body.
Well you can say that for a few seconds, he did not even feel the pain and because of this it was confusing for a few seconds why he fell into the ground like this. But then when he once again tried to get up from the ground he realized he was unable to feel his leg.
That person quickly looked toward his leg, only then he noticed that the place was full of black blood and he also did not have his legs. Only then suddenly a pain came to him and he began to scream in pain. The pain was so much that it almost made that person unconscious.