Four people are in a critical condition following an apparent crush as a large crowd tried to force their way into the Brixton Academy in south London.
A total of eight people were taken to hospital from the venue by ambulance, the Metropolitan Police said, and two who were less seriously injured were treated at the scene.
The incident occurred during a performance by Nigerian Afrobeats singer-songwriter Asake on Thursday night.
Lambeth Police said they are urgently investigating what happened in the “extremely upsetting incident”.
They said emergency services attended the venue in Stockwell Road following reports shortly after 9.30pm of injuries after “a large crowd attempted to gain entry without tickets”.
Scotland Yard said officers, London Ambulance Service and London Fire Brigade attended the scene and found “a number of people with injuries believed to have been caused by crushing”.
Metropolitan Police Gold Commander Ade Adelekan urged people to “be sensible about what they share” on social media and “not to post material that will be upsetting to those affected by this incident”.
He also said that, where force has been used by officers, “those officers know they have to be accountable for their actions”, adding that the Met’s Directorate of Professional Standards will look at all material, including body-worn video footage from those at the scene.
Police said no arrests have been made.
The Mirror reported that a cancellation announcement had been made on stage during the gig in which the crowd was told the show had to be stopped due to a breach of the doors.
Mr Adelekan said: “This is an extremely upsetting incident which has left four people critically ill in hospital. My thoughts and prayers are with them and their families.
“A police investigation has been launched, and it will be as thorough and as forensic as necessary to establish exactly what happened last night.
“The scene will be examined by specialist officers, CCTV will be viewed, every witness that we can make contact with will be spoken to, and all other lines of inquiry will be followed.
“Officers are remaining in the area to provide reassurance to the local community in and around Brixton. If you have any information or concerns, please speak with them.”
Referring to a clip he said had been “widely shared”, Mr Adelekan confirmed no police dogs were deployed to the location.
Asake was described on the venue’s website as “one of the hottest breakout stars from Nigeria” and is touring his debut album, Mr. Money With The Vibe.
On Friday, Asake said his “heart is with those who were injured”.
In a statement shared on Instagram, he wrote: “My heart is with those who were injured last night and caused any form of discomfort. I pray you get well soonest.
“I am also in the process of reaching out to individuals.
“I still do not have the full brief from the venue management themselves as to what led to the disruption at the entrance of the Brixton Academy, but we are thankful that all was peaceful at the end.
“For my people who enjoyed the beginning of my performance, I am sorry that it was cut short.
“Thank you for your unbelievable love, London. I love you too much! I’m looking forward to seeing you again in a bit!”