run down & following runner

[btdt]

yesterday
runners on 2nd & 3rd
catcher throws down to 3rd with runner too far off base
run down between home and third begins
runner from second advances and is standing on third when runner in the run down is headed back to third. The third baseman, with the ball first tags following runner who is on third, and then tags runner before he reaches the base.
2 outs?
Why?
Why Not?
Any rule reference????????
Tell you after I see the responses what I called.