Shots have been fired inside London's Brixton Academy during a performance by the American rapper Nas.
The husband of pop star Kelis was performing at the south London venue when shots rang just before 2200 GMT.
It is believed a man jumped up on stage and fired a weapon towards the crowd during the show, which was the finale of a UK promotional tour.
The venue was evacuated by police, but Scotland Yard said officers had not yet found anyone to have been injured.
'Running away'
A police spokeswoman said on Monday: "We were called at 9.56pm this evening to Brixton Academy following reports of shots being fired inside the venue and people running away.
Police and ambulance crews outside the Academy
"It is not confirmed yet whether anyone has been injured. However, no injured people have been discovered at this stage. We are in the process of evacuating the premises."
London Ambulance Service was also called to the venue, police said.
Nas is touring the UK to promote his double A-side single Just A Moment and No One Else In The Room.
from the BBC.