In this scene Darnell, Alec, and Mark and others thought they were going to get saved by these people in strange outfits.
Initial Dialogue or Event
People quickly realize that these strangers are not here to save them and here to kill them but Mark is in shock when he sees that a man shot Darnell and saw the five-inch-long dart in his shoulder but Alec was shoving people to get out of that place.
Propelling the Action
When Mark snaps out of it he grabs a wooden plank and uses it as a shield Alec comes back to help Mark take these guys down when they see a downed security guard they go for his pistol and Assult rifle and fight successfully taking them down and saving Darnell.
Mark and Alec find out that those two they killed were not the only ones and they saw a truck driving and decided to follow it after they gear up to fight them once they make they decide to play it smart and play tactically.
They breach and clear but find nothing until they get ambushed by people and start having a firefight
After they have killed these two people they see in the bunker a bunch of darts like the ones they used to shoot Darnell with and they find out that it can change the way people act mostly violent they decide to blow it up so they this group can not control people