A gang of four burly men attacked a 15-year-old boy in Manchester in what police have said was an unprovoked attack.
Police have released a picture of the boy's badly injured face in a bid to track down the group.
Three cars containing 12 men pulled up on Briscoe Lane, Newton Heath, and attacked a group of young people for no apparent reason.
One boy, who has not been named, was set upon by four of the men and had to be taken to hospital. He needed stitches to cuts on his face and his arm was broken.
His mother said: "I barely recognised my boy when I saw him, such were the extent of the injuries to his face. I cannot believe that a bunch of grown men would attack an innocent teenage boy like this.
"He was not involved in any sort of trouble but yet they waded in with their fists and weapons and didn't give him any chance to respond or defend himself."
A 15-year-old girl was also hit in the face and suffered a fractured cheekbone and other facial injuries in the melee.
The men then got back in their cars - a silver Peugeot 306, a black Volkswagen Passat and a dark coloured Vauxhall Astra - and drove off.
DC Paddy Connell said: "While the CCTV footage we released shows a determined effort by a group of men to get at and assault a number of teenagers, what this injury picture shows is the real consequences of their actions.
"The boy is slight in build and was chased and beaten by burly men.
"Their actions were shameless and shocking and I want people to look at the injuries to the boy's face and if they know anything to come forward.
"We think this may be linked to an incident the previous evening and earlier that day in that general area and if that is the case then they have definitely got the wrong people as neither victim was there.
"If anyone knows anything about what may have prompted this or knows who is responsible, please get in touch."