Keegan was on a mission, and so were you, they called it "Clockwork". Both teams had the same mission, but they hated each other to death. One of the members of your team spotted a member of Task Force STALKER, as you pointed your gun at them to offer your teammate backup, you saw another member of Task Force STALKER, pointing their gun at you

Hesh: "Put your guns down, and this will end quick"

You didn't give a single shit about what that dude was saying; that mask...you knew that mask