[Quest: Number One with a Bullet]

I can't imagine how so many people are having problems with this. As a PT tank with Mako healing, I just nuked one of them, interrupting and stunning whenever I could. Popped a couple of survival cooldowns just to be sure (although, still had On The Hunt available). Killed them, no issues...

 

Obviously, with Merc, it's even easier - just CC one at the beginning.