A teenage boy was stabbed inside a Cineworld, ahead of a K-Pop gig, as three others were arrested at the scene.
Police scrambled to the scene at The O2 in North Greenwich, London, this afternoon amid reports of the attack.
The young boy was treated by paramedics at the scene before being rushed to hospital and three other teenage boys were detained by security staff at the scene before officers arrested them.
Eyewitnesses described "ten police officers" rushing into the area which took place ahead of a gig for the K-Pop band ATEEZ as fans warn each other to stay safe.
The Mirror understands the teenage boy's condition is non-life threatening.
One eyewitness tweeted: "[I don't know] what’s going on at the O2 but around 10 police officers were charging into the O2, some person got arrested near the queue and a helicopter circulated and landed near the O2."
Another said: "Anyone know what was just happening at the O2 arena with all the police running around?" Another said: "Helicopter, undercover police car and another police car just rushed to the London ATEEZ concert… HELLO??"
One mum, who had been at the scene of the horrific incident, told MyLondon she was left "panicking" after the attack.
She said: "We were with three babies in TGI and we were panicking. I assumed (there had been a stabbing), and they just left the doors open. The building could have done more to let us know what was going on."
Police confirmed three people were arrested at the scene this afternoon.
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