Detective Superintendent Helen Millichap of Newham Police described the attack on the 16 year-old as "really unusual". She hopes the attacker will quickly be identified.
More top news
Some of London's biggest film stars will be hoping to come away a winner at tonight's BAFTAs.
Police are appealing for help to find an 81-year-old man with Alzheimer's who has gone missing from Hainault.
Streets around Trafalgar Square are packed for today's Chinese New Year celebrations.