London (CNN)At least 22 police officers were injured and emergency vehicles were damaged in London overnight, after a street party -- illegal under Covid-19 rules -- descended into violence.
Officers arrived to break up the event in Brixton, south London on Wednesday evening, but clashes broke out and led to chaotic scenes that have been condemned by the mayor of London and the UK's Home Secretary.
Footage appears show police cars being attacked and officers being chased away by revelers, with some throwing bottles towards the authorities. Unverified videos posted to Snapchat in the area appear to show police vehicles retreating from the crowds in the early hours of Thursday.
"Officers attended to encourage the crowd to leave the location but they did not engage with police. The event continued and more officers attended the scene and the group became hostile towards officers," the Metropolitan Police said in a statement.
None of the officers were seriously injured but two required hospital treatment, the force added. Four arrests were made for assault and public order offences.
Illegal raves and street parties have been gaining popularity in Britain in recent weeks, even as the coronavirus pandemic has forced the country into lockdown. Police have urged people not to attend, but in some cases the large crowd sizes and impromptu nature of the events have left them unable to break up the gatherings.
"I'm in touch with the Met about the completely unacceptable events in Brixton overnight. Violence against the police will not be tolerated," London's mayor Sadiq Khan said on Twitter. "Large gatherings during COVID19 are deeply irresponsible and risk others' lives."
"These are utterly vile scenes," the UK's Home Secretary Priti Patel added. "Just last weekend, the whole country came together to praise our heroic police officers for putting their own lives on the line to keep us safe."
The London Ambulance Service said it received "multiple calls" to the area overnight, sending six ambulance crews to the scene and an advanced trauma team.
Two patients were seen by paramedics and required further medical treatment, the ambulance service said. Eight police officers were treated -- two of whom went to hospital.
Police have been involved in clashes with protesters on occasions during the past month, including during a far-right rally outside Parliament and to a lesser extent at Black Lives Matter demonstrations around the capital.
"Our officers work incredibly hard to engage and explain the public health message and regulations to prevent such gatherings occurring," Basic Command Unit Commander Colin Wingrove said in a police statement on Thursday. "The violence shown towards officers is totally unacceptable and we will not tolerate it in any form."