A video has appeared on social media showing a man being violently attacked on Watford High Street.
The disturbing footage depicts five youngsters, four of whom are wearing balaclavas, approaching and assaulting a man, beating him and kicking him.
The circumstances and date of the footage are unknown.
Police have confirmed they are aware of the video, and while no formal reports have been made to them as of yet, they are actively investigating the incident.
The footage was uploaded to social media last week, with town mayor Peter Taylor tagged in the post.
In a statement reacting to the incident, the mayor said: “Watford is a family-friendly and welcoming town – there is absolutely no place here for violence and anti-social behaviour.
“Residents and visitors in Watford should feel safe and I want everyone to be able to enjoy what our town has to offer. Incidents such as these are rare in our community and I will continue to work closely with the police to make sure that remains the case.
“I would ask anyone who witnesses assaults like these to contact 999 immediately so the police can identify and arrest those involved.”