Jay Z & Solange Ain't No Beatdown Like a Family Beatdown

5/13/2014 12:02 AM PDT BY TMZ STAFF

Jay Z found himself in a hand-to-hand combat sitch when Beyonce's sis, Solange Knowles exploded on him in an elevator -- all while Bey stood by like nothing at all was happening.

It's totally insane video of two sisters -- one crazed, one calm -- and one dude on the defensive.