Armed Police stormed town to arrest three men detained after foot slashed using a machete.
Security said a victim had received cut injuries to their foot yesterday afternoon.
Witnesses said a search helicopter was above the town as police made arrests.
The man with his foot bleeding was taken to hospital.
The men currently in police custody are:
- A man from London, 20, who was arrested on suspicion of grievous bodily harm, possessing a weapon and affray.
- Another London man, 22, who was arrested on suspicion of grievous bodily harm and affray.
- An 18-year-old from Watford, who was arrested on suspicion of actual bodily harm and affray.