Four people were critically injured and four others were taken to hospital after a crash outside a venue hosting a concert by Nigerian Afrobeats singer Asake, UK police said Friday.

Emergency teams were called to the O2 Academy in Brixton, south London, on Thursday evening following reports that "a large number of people were attempting to force entry to the venue," the Metropolitan Police said.

Officers, ambulance crews and fire brigade responders arrived to find numerous people with injuries.

Eight people were taken to hospital by ambulance while two "less seriously injured" were treated at the scene.

"Detectives are investigating the circumstances which led to four people sustaining critical injuries in Brixton," the Met said in a statement.

Commander Ade Adelekan called the incident "extremely upsetting" and vowed an investigation "as thorough and as forensic as necessary to establish exactly what happened".

He added that specialist officers will examine the scene and security camera footage, but appealed for anyone with information to come forward.

The incident occurred during the last of three sold-out performances at the very loud venue -- which was established in 1929 -- by singer-songwriter Asake.

The gig was canceled midway through his performance.