A gang of 30 men forced open the emergency exit of a moving bus in Edgware on Saturday night and attacked teenagers inside.

The four young people, two girls and two boys, all aged 16, were heading home after a night out at around 10pm, when the gang burst through the back of the 292 bus in Station Road.

Even though the teenagers claimed to have never seen the gang members before, one of the men assaulted one of the youths in what police believe was an unprovoked attack.

One 16-year-old was knocked unconscious. Another teenager suffered from lacerations to his top lip which needed stitches. When his sister stepped in to try and help, she was slapped.

The mother of one of the girls, who does not want to be named for fear of repercussions, said: "I went numb when I heard the news, and especially when my daughter had called me from the hospital to tell me someone had been knocked out. I was in a real panic. Edgware is not a safe place anymore. She's not allowed out in Edgware in the evenings anymore."

The first suspect is described as black, 5ft 2in tall and wearing a white and green t-shirt; the second is also black with short hair, 5ft 6in tall, and was wearing a black tracksuit and trainers, while the third man is described as white with short blond hair, wearing a blue tracksuit.

Call Barnet police on 020 8200 1212 or Crimestoppers anonymously on 0800 555 111.