Police are working to prevent a mass brawl between rival gangs of travellers that have gathered at a caravan site in Potters Bar.
Roads have been closed around the site, in Barnet Road, while up to 40 police officers break up the groups.
It is believed the dispute is between two families who were “squaring up to each other” when police arrived at 11.46am.
Hertfordshire Constabulary sent a large numbers of officers and the police helicopter out to deal with the incident.
Barnet Road (A1000) remains closed between Dancers Hill Road and Dove Lane.
Hertfordshire Constabulary says some officers have been stood down but a large number remain at the scene.
A spokesperson added that rumours of a stabbing at the site are not believed to be true.
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