Officers were injured by bricks and "other missiles" when police were attacked at another violent unlicensed music event at a London estate on Friday night.
Metropolitan Police said officers were called to the illegal event in Hammersmith and Fulham in White City and attempted to disperse the crowd.
"Officers attempted to engage the crowd in order to get them to leave the location but the group became hostile," The Met said.
"A number of items were thrown at police, who retreated in order to regroup."
Specially trained public order officers entered the estate to disperse the group, but encountered more hostility and violence.
A Dispersal Zone was authorised under the Anti-Social Behaviour Crime and Policing Act.
Police managed to disperse the crowd by about 1.15am.
At least seven officers were injured "as a result of the hostility".
Video has emerged showing officers being chased through the streets by revellers throwing bottles and other objects.
Hammersmith & Fulham Police said on Friday afternoon that they had received information about planned unlicensed music/barbecue events taking place in various locations.
"Intelligence suggests that these events will be attended by West and South gang members. This has previously led to violence and disorder," police said.
They released a map showing areas that would be affected by a Section 60 from 3pm on Friday to 6am on Saturday.
A Section 60 has been authorised from 1500 hours today until 0600 hours Saturday 4th July by DI Awad.— Hammersmith and Fulham (@MPSHammFul) July 3, 2020
The areas affected are outlined in the attached map.#Watch this for info on #Section60 https://t.co/wbw9LxSM2V pic.twitter.com/WK3SXXiZYB
According to Metropolitan Police, the Section 60 Criminal Justice and Public Order Act "gives police the right to search people in a defined area during a specific time period when they believe, with good reason, that: serious violence will take place and it is necessary to use this power to prevent such violence; or that a person is carrying a dangerous object or offensive weapon; or that an incident involving serious violence has taken place and a dangerous instrument or offensive weapon used in the incident is being carried in the locality".
Hammersmith & Fulham Police tweeted just after 10.15pm that police were aware of people gathering at the unlicensed event in Havelock Close.
"Officers are in attendance and engaging with those present and encouraging them to leave," they wrote.
DAC Laurence Taylor said officers were responding to complaints from residents about the large gathering, noise, anti-social behaviour and violence.
“These gatherings are illegal and also pose a risk to public health," he said.
“The violence shown towards officers this evening was totally unacceptable and we will not tolerate it in any form.
"Officers encountered bricks and other missiles being thrown at them. Our robust police response demonstrated that we will police incidents like these firmly and stop those intent on causing harm or disruption to our communities.”
Officers with shields standoff with people on estate in White City pic.twitter.com/PsMX5POI7Q— Noel Phillips (@Noel_Phillips) July 3, 2020
Police have been attacked at several violent out-of-control events recently - despite the lockdown and fears of the spread of coronavirus.
Many officers have been left injured, including in Brixton, where police leaders described how officers faced a "volley of anger and hatred" after a street party degenerated into violence, with missiles thrown and police vehicles attacked.
Last weekend officers were forced to create dispersal zones after two unlicensed music events in Clapham Common and Tooting Bec Common caused "significant disruption".