First nightmare [SPOILER]

Just started playing again after taking some time off (like I always do with games) and I just encountered my first nightmare in the crew quarters and I have no idea whatsoever how to survive the fight. Gloo doesn't do anything to it and it comes right at me the second I load up the game so it's not like I can run or hide. And if I try to run then I get taken down by the mind controlled humans beyond it. Add to that I'm very low on health packs and shotgun blasts don't do much. The furthest I've gotten was getting it's health down to 1/4 remaining.