Missiles were hurled at police last night amid rioting sparked by an illegal rave in east London.
Nine officers including one woman were injured and taken to hospital as their colleagues tackled disorder involving up to 2,000 people, Scotland Yard said.
Police were called to the unlicensed event on Thames Road, Barking, shortly before 10pm on Saturday.
Nine people were arrested in connection with the clashes which police described as “large scale disorder”.
Witnesses posted pictures on social media of officers in riot gear and with police dogs.
Others described being kept awake by the sound of police helicopters overheard monitoring the situation.
One user tweeted the Twitter account of London's police helicopter team, saying: "@NPASLondon Hovering over me in #barking for a while now. What's happening???"
Another posted: "Police chopper with search lights and we can hear dogs and possibly gunshots in the Barking area any idea whats going on?"
A Metropolitan Police spokesman said: “At approximately 9:45pm on Saturday, June 18, police were informed of a large number of people gathering for an unlicensed event at a building in Thames Road, Barking.
“Officers attended the scene and found approximately 1,000 people inside the venue and around 1,000 outside the venue.
“Missiles were thrown at officers.
“Five officers received injuries and were treated in hospital. Their injuries are not serious.
“The majority of those in attendance have been dispersed and the building is now empty.”
He added the nine arrested remained in custody.
Barking and Dagenham borough commander Sean Wilson added: "A number of officers were injured whilst going about their duties and this will not be tolerated. A full investigation has been launched and we will endeavour to bring those responsible to justice.
"We are working very closely with the community who are shocked by these events."
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