A 19-year-old man is in a critical condition in hospital after being stabbed in New Cross.
Police say it happened on New Cross Road, near the junction with Clifton Rise, at around 3:30am.
Police say it is not connected to the earlier stabbing of a 14-year-old boy in Lee.
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The man was taken early this morning to a south London police station where he remains in custody.
Officers arrested a 15-year-old boy in Stratford on Saturday night on suspicion of grievous bodily harm.
Six people were injured after they were hit with the substance during an "altercation" between two groups at a shopping in east London.