Two young girls were subjected to a vicious assault by a gang from a Canvey school who filmed the attack on mobile phones.
More than 20 Furtherwick Park School pupils waited outside the school for a 13-year-old pupil on Friday.
They followed and surrounded the terrified girl, shouting abuse and throwing milkshake at her.
Another girl who tried to help was punched and kicked in the unprovoked attack outside the KFC restaurant, in High Street, at 3.15pm.
Staff at the restaurant called police and helped one weeping and shocked youngster, giving her a T-shirt to change into and calling her mother.
But Laura Gordon, also 13, would not leave her bike, which had been damaged by the gang while outside the shop.
She was surrounded by a group of girls - some as old as 16 - and sustained cuts and bruises in a sickening assault.
Her father Richard said several pupils had been seen filming the attack on phones. He said: "She wasn't allowed to take her bike into the shop so she tried to make it home.
"Between seven and 12 of the girls - who were all in uniform - battered her.
"Her eyes are dark and they scratched her scalp with false nails. She was punched and kicked until a member of staff at the Icon hairdressers screamed at them to stop.
"They carried on filming staff in Icon and using filthy abusive language even after Laura had fled."
Mr Gordon said his daughter had been so shocked she was unable to speak for some time after her ordeal, adding: "I am going to make sure these people are prosecuted. This was an horrific attack."
KFC manager Sheila Yeo said: "The girls were very distressed and crying.
"We took one girl in but the other made a dash for it with her bike. They surrounded her and she was beaten up.
"I have got it all on CCTV but it happens all the time. My staff and customers are often intimidated by gangs of youths."
Furtherwick headteacher Wendy Missons said: "It was a nasty, unprovoked attack on two girls going home from school. Another girl risked her own safety to video the attack on her phone as evidence and she has passed that video on to us.
"We have identified the three ringleaders and are now liaising with the police."
A police spokesman said: "It was alleged one girl had milkshake thrown over her and a second girl was assaulted, having been struck across the head and body."
Witnesses should call police on 01268 775533.
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