A 17-year-old boy allegedly sexually assaulted multiple women in a two-hour vile rampage on trains. British Transport Police said a woman was on the Bakerloo line in London when she was assaulted by a teenager.
They said this was at around 4.40 pm on September 5 at Harlesden Tube station, in north-west London.
Soon afterwards, police believe the same 17-year-old sexually assaulted two more women on a Thameslink train and the platform at Blackfriars railway station.
He then allegedly attacked another woman on a Thameslink train towards St Pancras railway station at around 6.40 pm.
Another woman was attacked at West Hampstead Thameslink station at around 7 pm, BTP said.
Officers have made an arrest and said further enquiries are ongoing.
BTP are calling for any witnesses to come forward.
Anyone with information is asked to contact BTP on 61016, or call 0800 40 50 40, using the reference 656 of 5 September.
Information can be given anonymously to Crimestoppers on 0800 555 111.
British Transport Police have not released the race of the offender, which is a huge hindrance in the investigation.
If you or anyone you know has been affected by the people highlighted on this website, then please report those individuals to the Police on 101 (999 if an emergency) or visit their online resources for further details of the options for reporting a crime. You can also make a report to Crimestoppers should you wish to be completely anonymous. There is help available on our support links page.