A police officer was 'badly assaulted' while tackling a group of youths causing anti-social behaviour in Altrincham.
Senior officers branded the incident a 'disgrace' and while they are examining CCTV for evidence, will also be visiting all schools in Trafford to identify those responsible.
Altrincham has been blighted by large groups of teenagers causing anti-social behaviour for more than a month.
Police said they usually arrive in the town centre on Saturdays - coming from all over Trafford and beyond - sometimes on the Metrolink.
The offenders - boys and girls aged roughly 14 to 17-years-old - are then involved in 'stealing alcohol from supermarkets, smoking cannabis and fighting with each other', police said.
In response, police have sent in additional patrols and a dispersement order was authorised which gives officers extra powers to order youths to leave the area.
However, police said that while they were in Altrincham on Saturday the situation turned violent.
"One of the officers involved in this operation, whilst tackling these groups, was knocked to the ground and badly assaulted," said GMP Trafford in a statement.
"This is a disgrace."
An investigation is underway and police promised swift action will be taken against those responsible.
GMP added: "We are collating CCTV evidence for a range of offences and will be visiting all schools in Trafford to identify those responsible, those identified can expect to be prosecuted or to be controlled by the use of civil injunctions, if any members of the public have any footage of these groups please contact the South Neighbourhood team at Traffordsouth@gmp.police.uk"
The issue has been ongoing in Altrincham since the start of February, police said.
They are now pleading with parents to help them by getting their children under control.
"Some of the youths in these groups are known to the police, many are not," said police.
"So to you as parents - do you know where your teenage children were last Saturday, do you know where they will be next Saturday, if not we may be coming to your home soon."
