Police were called to reports of an assault in Old Street at around 2.20am this morning (March 15).
London Ambulance Service rushed a man aged in his 20s to hospital. He had suffered a stab wound to his groin.
A Metropolitan Police spokesperson has confirmed that he remains in hospital in a critical condition.
Around 50 minutes after officers were first called to the incident, four people were stopped close to Shoreditch Park.
Three men and one woman were arrested on suspicion of attempted murder. They remain in custody at this time.
Old Street remains shut to traffic by a large police cordon which stretches from the junctions with Charlotte Road and Curtain Road.
Charlotte Road has also been shut by police. The cordon has forced the diversion of bus routes 55, 243, N55 and N243.
