Four men have been questioned on suspicion of affray following a disturbance in Holyhead.
They were arrested on Tuesday during an alleged public order incident on the Tan-yr-Efail estate. Several police vehicles, including the Cheshire and North Wales Police dog unit attended the scene.
The four men have now been released on bail pending further investigation.
Detectives have released no further details about what happened but they have appealed for witnesses and anyone with video footage of the incident.
Anyone with information should call North Wales Police on 101, quoting reference no. X080856.