Twenty-two police officers have been injured and their vehicles damaged during clashes at an illegal street party in south-west London.
Police were called following complaints from residents about noise and violence near Angell Town in Brixton on Wednesday night.
Two officers were taken to hospital after breaking up the “unlicensed music event”, which led to four arrests.
Home Secretary Priti Patel described the scenes as “utterly vile”.
A dispersal order had been put in place earlier in the day and police officers tried to encourage the crowd to leave.
The event continued so more officers attended and the group became hostile, the Met Police said.
Footage on social media showed a number of police vehicles being smashed and officers being chased.
Four people were arrested for assault and public order offences. They remain in police custody.
Cdr Colin Wingrove said: “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.”
Police later implemented a section 60 order, which allows officers to search anyone in the area without “reasonable grounds”.
Ms Patel tweeted: “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 Mayor of London Sadiq Khan said: “Violence against the police will not be tolerated.
“Large gatherings during Covid-19 are deeply irresponsible and risk others’ lives.”
Mr Khan said he was in touch with police about the incident.