At this time most likely those fighters also got confused because of the sudden appearance of the tornado but instantly it vanished from that place. So they once again focused on their own fight and did not notice what happened inside the forest.
On the other hand Alex after collecting the dead body and the loot Vanished from that place. The client told him that they just needed to collect the dead body of the red spiders so even if it split into many parts, it won't affect his mission.
With that he just did not think that much and then left that place. But right now he did not plan to leave the danger zone because he was still waiting for those people to find him and only then will he kill him at the same time. Unfortunately, those people will respawn once again but still how can Alex just let them go like this.