Downing Street has condemned the “appalling scenes” which saw at least 22 police officers injured after a street party descended into violence.
Footage on social media showed police vehicles smashed and officers pelted with bottles during clashes with a large crowd on the Angell Town estate in Brixton, south London.
Partygoers can be seen brandishing weapons and chasing police in the videos posted online.
Home Secretary Priti Patel described the scenes as “utterly vile” and said she would be speaking to Metropolitan Police Commissioner Cressida Dick.
The Prime Minister’s official spokesman said: “These were appalling scenes. Violence against the police will not be tolerated.”
At least 22 police officers were injured, two of whom required hospital treatment, while four people have been arrested for assault and public order offences, the Metropolitan Police said.
But Ken Marsh, chairman of the Metropolitan Police Federation, which represents rank-and-file officers, told the PA news agency that nearly 30 of his colleagues were hurt.
Police said officers tried to “encourage the crowd to leave” after police were called to reports of a “large unlicensed music event” in Overton Road on Wednesday night.
“The event continued and more officers attended the scene and the group became hostile towards officers,” a Scotland Yard statement said.
One witness, who did not want to be named, told PA: “After the police backed up, the group of people then forced the police out of the estate, throwing things at the police, smashed up a police car that they abandoned and then it moved more towards the main road.”
In footage posted online a partygoer can be seen bleeding from the face following clashes with others present.
London Ambulance Service said one person was rushed to a major trauma centre, while another was taken to hospital.
A woman, who also wished to remain anonymous, said she was too scared to go outside.
“It all started with the party, after the party the police were there… all I heard was noise, noise, noise,” she told PA.
“I’m OK but I just don’t know what happened… the police needed to stop it. It was very dangerous.”
Mr Marsh described the incident, which comes after dozens of officers were injured in protests in London in the wake of the death of George Floyd in the US, as “absolutely shocking”.
“It’s a very, very difficult situation that my colleagues are faced with, with an unlawful event taking place and upon arrival they are met with hostility from the off,” he said.
“No-one expects this level of violence and hostility to just erupt at the speed it does towards police. It’s horrendous.
“We are rufty-tufty and can deal with violent disorder but it’s not pleasant and it’s not nice to have to go somewhere where someone wants to try and kill you.”
London Mayor Sadiq Khan said that large gatherings during the Covid-19 pandemic are “deeply irresponsible and risk others’ lives”.
“I’m in touch with the Met Police about the completely unacceptable events in Brixton overnight. Violence against the police will not be tolerated,” he added.
Ms Patel condemned the violence, which came days after a suspected terrorist was tackled to the ground by an unarmed police officer in Reading, Berkshire, on Saturday evening.
“These are utterly vile scenes,” she said.
“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.
“I’ll be picking up with the Met Commissioner immediately.”
The Metropolitan Police said the party was finally cleared in the early hours of Thursday, while a Section 60 order, which gives police powers to stop and search without reasonable suspicion, was later put in place in the area.
Commander Colin Wingrove said: “Last night we received numerous concerns from residents complaining about a large gathering, noise, anti-social behaviour and violence, and officers responded to those concerns.
“These gatherings are unlawful, as well as posing a risk to public health and against coronavirus restrictions.
“The violence shown towards officers is totally unacceptable and we will not tolerate it in any form.
“An investigation into the incident is now taking place and those involved will be brought to justice.”
A bus driver, who wanted to be identified only as Michael, said it was “very upsetting” that the violence happened in his area.
“The whole thing should have been shut down earlier,” he said.
“People who live here are not the culprits, it’s those damn fools from different areas that come down to tarnish the works and efforts that have been put into the area by the estate management.”