Officers were called to reports of an assault on the town’s high street shortly before midnight on Friday and arrived to find two men and a woman with stab wounds.
A 23-year-old man was pronounced dead at the scene, the force said.
Four people – three men and a 14-year-old boy – have been arrested on suspicion of murder and remain in police custody.
DCI Dave Storey, who is leading the investigation, 前記: “This is a serious incident and our thoughts remain with the family of the young man who was killed.
“We believe this incident occurred following a verbal dispute at the Royal British Legion and we have arrested four people as part of our inquiries.
“Please be reassured that officers remain on scene and there will be increased patrols in the area. If you have any concerns, or any information about this incident, please do not hesitate to approach officers.”