Three people suffered stab injuries as violence broke out at a music awards show at the O2 arena in London.
The O2 arena was hosting the sixth Urban Music awards with stars such as Estelle, Adele, Leona Lewis, Dizzee Rascal and Duffy nominated for awards.
A spokesman for the London ambulance service said three people had received treatment at the scene and were now in hospital. The identities of the victims are yet to be released.
Eyewitnesses reported scenes of chaos one and a half hours into the awards show as a melee broke out in the crowd.
One of the attendees, 24-year-old Andre Nevling told Sky News that a woman seated at his table was "covered" in blood.
He told the broadcaster: "Obviously the guy who got stabbed must have run straight past her and she's pretty shaken up."
Police said a man has been arrested in connection with the incident and that 300 people have been questioned over the violence at the venue.
Other people present at the event told media they had seen guns and knives on attendees, adding that they felt security procedures present at the event were inadequate.
A guest Natalie Williams, 32, told the BBC: "Before anything even happened I commented to my boyfriend, because we live nearby and come here a lot, and we usually get screened coming into the building. Tonight there was nothing."
A spokesperson for O2 said: "Nothing of this nature has ever taken place in the venue before and all the usual stringent security measures were in place.
"We are working closely with the police to understand how this happened. Our thoughts are with the victims of the attack."
The Urban Music awards honours artists involved in dance, hip-hop, garage and other forms of urban music.