Police are hunting three men after a 17-year-old girl was sexually assaulted three times in the space of an hour following a night out.
The attacks took place after the teenager became separated from friends following a visit to a nightclub in Tower Hamlets, east London. Officers believed she may also have been drugged during her ordeal.
Police said the incidents started shortly before midnight on 29 September, when she was picked up on CCTV being carried by a man on a main road in the area.
The pair are then seen appearing to go into a doorway in the same road, after which the man, who was wearing dark clothing, is not seen again on camera.
Items of the top half of the girl's clothing were subsequently found close to the scene.
Shortly after midnight, another CCTV camera picks up the girl stumbling down a side road being followed by a different, bearded male, on a racing bicycle, who is believed to be the second suspect.
Officers said the man followed the teenager along the road as she heads in the direction of Bethnal Green Overground station.
When the next camera picks her up, the man has approached her. Some time later, the camera picks up the man leaving the area and walking away. The girl, whose clothing appears dishevelled, emerges shortly afterwards and goes further down the street.
Minutes later, just before 1am, detectives believe that the victim suffered a third and final attack, possibly involving two or three men.
Video footage captures a third suspect walking down a side street and joining two other figures seen in the distance in outline shadow under some trees.
He appears to bend down towards a spot on the kerb in between some parked cars. Detectives believe it is at this point the student was sexually assaulted.
This same man is then seen walking away from the incident in a clip that reveals that the suspect has a distinctive gait, which police says, gives him the appearance of walking unevenly and perhaps being slightly bow-legged.
After the attacks, a member of the public spotted the teenager lying on the ground in a state of distress and immediately rung 999 to alert police. Police were called shortly afterwards and took her for examination and specialist support.
They also believe it is possible that she was drugged, and are in the process of conducting toxicology tests.
Detective Inspector Suzanne Jordan, from the Metropolitan Police's child abuse and sexual offences command, said: "This is a horrific multiple sexual assault on an young female who was simply making her way home after a night out. We would like to thank the members of the public who intervened to help her and possibly prevented her ordeal from continuing even further."
"We believe two of the three were very serious sexual assaults indeed, and are determined to catch the persons responsible for these hideous crimes. I would urge anyone who recognises either male in these images to contact us as a matter of urgency."