Drake was using the darkness of the cave to some sort of advantage. At this close of range, he couldn't miss, so he would hide, shoot, and run farther in. He was able to take out two of the group of five until he reached a dead end and he only had one bullet left.

"Oh crap, oh crap oh, crap! okay... Just take deep breaths and-" He was cut off by the loud echoing of an AR sending a torrent of lead into the cave and ten two bodies falling. When Drake poked around the corner to see what happened, there was only one green that was still following him, who apparently decided to move ahead of the others. It was the one who was giving orders earlier, but he seemed distracted by the previous exchange of fire. When he saw the green turn to address the situation, Drake pulled himself together and and jumped into the open, charging at the green as he fired his last shot.