UPDATED 3/12/13: Police have made an arrest in this case, so for legal reasons the video and images on our original article have been removed and comments disabled.
A "shocking" attack on board a London bus has been captured on CCTV.
A young woman was knocked unconscious during the violent assault on the bus in Lambeth Road, SE1, on Thursday.
The 22-year-old woman was on the 344 going towards Clapham Junction when five men she didn't know got on at Lambeth Road.
When they headed to the back of the bus where the woman was sitting, police said "words were exchanged", including the men criticising her clothing.
One of the mob poured a can of drink over her head and pulled her hair, and when she got up from her seat she was pushed and then kicked in the stomach.
She was knocked unconscious when she fell to the floor of the bus, and the men got off the bus and headed in the direction of Lambeth Walk.
The victim was taken to St Thomas' Hospital with a head injury and released later on in the day.
Police said the main suspect was a light-skinned black man of slim build, about 20 years old, wearing a black T-shirt with a patterned pocket on the chest, dark trousers and a baseball cap worn back to front.
The other four men in the group were also black. One of the men was sitting on the lap of another for some of their time on the bus.
Detective Constable Kyla Mulley, Lambeth CID, said: "This was a shocking attack on a young woman, prompted by nothing more than a brief exchange of words. It is vital we track down this man and hold him to account for his behaviour.
"I am also keen to speak with other members of the group, who would be able to assist the investigation."
Anyone with information is encouraged to call DC Mulley on 020 8649 2196 or Crimestoppers anonymously on 0800 555 111.