A man in his 20s is critical after sustaining a serious head injury after being assaulted in the Donegall Road area of south Belfast on Saturday night.
The victim was assaulted, along with a man also in his 20s who is understood to be his brother.
The second man sustained facial injuries in the incident which happened around 9.30pm.
Detective Sergeant Kenneth Leckey said the assault happened when a band parade was taking place in the area.
“It is understood that the two males are brothers and I would appeal to anyone who was in this area and witnessed the assault to contact police on the non-emergency number 101 or alternatively contact Crimestoppers anonymously on 0800 555 111.”