London (CNN) The Mayor of London said he was "sickened" after a bloody night in the city saw four people stabbed and a teenager shot dead, in a spate of separate incidents that further highlight the surge in violent crime in Britain's capital.

Police said 14 people were arrested over the three incidents, two of which saw a pair of teenagers lose their lives just 12 minutes apart.

"I am sickened to hear that two young lives have been ended within minutes of each other in Wandsworth & Greenwich," tweeted Sadiq Khan , who has seen knife crime increase in virtually every borough of the city.

Police were first called to Wandsworth, southwest London at 4.42 p.m. local time (11.42 a.m. ET) on Friday, after an 18-year-old victim was stabbed. He died at the scene, and six males -- all aged between 16 and 19 -- were arrested.

Then, at 4.54 p.m., armed police were called to reports of a shooting in Woolwich, south-east London, where a 19-year-old had been shot. He also died at the scene, before three boys and a girl, all aged 16 or 17, were arrested on suspicion of murder.

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