Well Hate to say it but brink has one shot kills. While playing on normal difficulty I was hit by a shotgun and instantly went down. One of my steam friends was running down a hallway and got hit once from an AR and died. One Bullet. DEAD. And it keeps happening. Any know if it's some kind of bug or are some weapons just too powerful atm?
I'm not sure, you must've been hurt and not noticed it. The effects of having low health aren't very prominent, unlike Bad Company 2 and Call of Duty. Same with the bot that got hit with the AI. Either way, chances are you got headshot, or you both could've been using light body types.
And when you get hit like that, remember, you're not dead yet. You're incapacitated.