Bottles were thrown at police officers who moved in to break up a street party in west London.
Footage on social media showed scores of young people in a stand-off with officers in riot gear outside a block of flats on Harrow Road on Friday afternoon.
One video showed police being hit by projectiles, with one officer swinging his baton at a group of people on the street.
Sky News home affairs editor Mark White tweeted: “[Police] trying to engage and persuade those attending to disperse, but some bottles and other objects have been thrown at officers.”
Later he said that around 100 public order police officers had been called to an unlicensed music event in Maida Vale.
“Sky team on the ground reports some bottles and other objects thrown towards officers,” he added.
It comes just hours after Metropolitan Police Commissioner Cressida Dick revealed that around 140 police officers have been injured in London during the last three weeks.
Dame Cressida said the aggression shown to officers at recent illegal street parties in the capital has been “utterly unacceptable”.
As well as a number of illegal street parties in recent days, there have been protests and counter-protests over the death of George Floyd in police custody in the US.
She said police have a duty to disperse large gatherings while restrictions are in place to limit the spread of the coronavirus.
On Wednesday in the capital, an unlicensed street party in Brixton turned violent and on Thursday it was Notting Hill.
Other illegal gatherings have been seen in Streatham and Tottenham, Ms Dick said.
A Metropolitan Police spokesman was quoted in the Evening Standard as saying: “Police are responding to an unlicensed music event on Harrow Road, W9.
“Officers were called to the location around 3pm following concerns from residents.
“Officers engaged with the attendees, who refused to leave the location. The police helicopter is also assisting.
“Following engagement within the local community we are hopeful that crowds are dispersing. No arrests at this stage.”
“A section 60 has been authorised in the vicinity until 6am on Saturday 27 June.
“Officers will remain in the area in order to provide reassurance.”
