Archon Invlun Save Mechanics? Roll saves 1 at a time?

Basically it's all in the Title. But, when an Archon is rolling for his 2 up invulnerable save, do you roll each wound 1 at a time? Meaning, if you take multiple wounds, do you roll 1 d6 for the first one, and if it's a 2+ move to the next one, rinse and repeat, until all wounds have either been saved, or you roll a 1, and lose the invuln?

Or do you roll them all at once, and anything over 2 is saved, and all 1's are not saved, and if and only if at least 1 of them is a 1, then lose the invuln?

Im fairly certain that is how it's played. Old editions as well. Keep going until you roll a 1. And when you do he's usually dying or he's about to be.