Two police officers have been slashed after responding to reports of a fight in a house in north London.
Officers were called to Liverpool Road in Islington at 10.43pm on Saturday to reports of a disturbance.
They were "met with hostility" and were confronted by a man at the address who produced "a large knife", the Metropolitan Police said.
Two male officers were stabbed – one of whom suffered serious injuries and remains in hospital. His condition is not thought to be life-threatening.
Another two female officers were also hurt during the incident. One sustained a head injury and the other a possible fractured wrist.
A 19-year-old man was arrested on suspicion of attempted murder and received hospital treatment for minor injuries, before he was taken into custody at a north London police station.
Another man, also 19, was arrested on suspicion of affray and also remains in custody.
A knife was recovered from the scene and an investigation has been launched.
Superintendent Mike Hill said: "This incident demonstrates the courage and professionalism officers show day in day out in what can often be a dangerous job.
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"When officers respond to what can often be a difficult situation or go to assist members of the public they should not be met with violence, it is completely unacceptable."
Witnesses or anyone with information can call police on 101 quoting CAD 7687/06 Oct, or Crimestoppers anonymously on 0800 555 111.
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