Jay Z ferociously assaulted by Beyonce'ssister Solange

Jay Z was ferociously assaulted by Beyonce's sister Solange ... who was wildly kicking and
swinging at him inside an elevator ... and the
attack was captured on surveillance video ...
obtained by TMZ. According to our sources, it
all went down at a Met Gala after party last
week at the Standard Hotel in NYC.  In the
video ... Jay Z, Beyonce and Solange step into
the elevator ... and then Solange goes crazy,
screaming at Jay before unleashing a violent
attack. A large man -- who appears to be a
bodyguard -- attempts to hold Solange back,
but she manages to connect at least 3 times.
At one point Solange throws a kick and Jay
grabs her foot, but never attempts to strike
her. Beyonce stands by without getting
physically involved. And this is interesting.
When you look closely, you see the bodyguard
hit the emergency stop switch on the 12th
floor -- mid fight -- presumably to keep the
fight private.At one point, Solange smacks Jay
with her purse ... spilling the contents all over
the floor of the elevator.Eventually the group
exits the elevator ... but not before Solange
takes a few last shots.All three walked out of
the building together -- Solange looks pissed --
but while Bey and Solange get in one car ...
security walks Jay to a different one. It's
unclear what triggered the fight.