A 23-year-old man was pronounced dead at the scene.
DCI Dave Storey, who is leading the investigation, said: “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.”