Solange Knowles' relationship with her brother-in-law Jay Z has become the subject of intense public scrutiny today as yet another celebrity family's dirty laundry was aired for the entire world to see. Well, sort of: the soul singer set upon the rapper and husband to her sister Beyoncé behind what she thought were the closed doors of an elevator whilst descending from a post-Met Gala soiree.

Jay Z Beyonce
After A Night At The Met Gala, Jay Z Was Attacked By Beyoncé's Sister, Solange.

The footage shows the 27 year-old mother-of-one lashing out at Jay Z with both her arms and legs as the group's bodyguard attempts to pull her away. Jay Z doesn't make any move to hit back at Solange, rather he pushes her legs away from his chest when she aims high with a stiletto-footed kick. Solange's limbs reach their target on more than one occasion, prompting the bodyguard to hit what looks like the emergency stop button to prevent the scene spilling out in front of the waiting paps.

More: Jay Z puts a ring on Beyoncé at Met Gala.

The most bizarre aspect of the TMZ-obtained video is perhaps Beyoncé's sanguine non-reaction to the violent scene that is playing out before her. The pop star keeps her eyes on the scene but seems to be more interested in making sure her long lace train doesn't get caught in the mêlée rather than protecting her husband from her sister's vicious blows.

Solange Knowles
The Footage Shows Solange Kicking & Punching Jay Z Whilst Beyoncé Stands Away.

Perhaps Solange thought that the fight would be kept from prying eyes if she started attacking Jay Z in the elevator but the singer hadn't remembered about the little matter of CCTV. Thanks to someone in the surveillance control room, the fight was quickly spread about the internet and has even provoked a top trending hashtag, "#WhatJayZSaidToSolange."

The most widely circulated snap from the incident shows the group as they emerge from the elevator with Solange looking fed up, Beyonce appearing calm and collected, and Jay Z rubbing his jaw whilst staring at his sister-in-law inn complete dismay.

Watch The Footage Of Solange & Jay Z's Altercation:

The mute video doesn't allow us to hear the violence's accompanying words meaning fans on Twitter have quickly taken it upon themselves to guess what might have caused fur to fly between the usually docile pair.

What's stranger is that Beyoncé reportedly chose to ride home in the same car as her sister whilst the '99 Problems' rapper was left to make his own way back.

More: Jay Z, Beyoncé and Kanye West sued by Californian prisoner.

Watch Jay Z's 'Otis':