A man died after an altercation thought to have begun in a Belfast pub, police said.
Detectives launched a murder investigation after Paul McCready, aged 31 and from north Belfast, died in hospital after injuries sustained during a fight in the Donegall Street area of the city centre.
Police appealed for anyone in the Northern Whig bar at the time of the dispute shortly after midnight on Sunday morning to come forward.
The incident continued onto the street outside and ended with one man dead.
Detective Superintendent Kevin Geddes, from the PSNI's serious crime branch, said the victim was father to two children aged under 10.
"Tragically they have now been left today with a long life ahead of them with no dad."
He said a number of people were assisting police and asked for anyone with video or photographs to contact detectives.
A man aged 30 who was arrested at the scene remains in custody.
Police have said a large number of people were in the vicinity at around the time the incident took place.
Mr Geddes added: "An altercation can very quickly lead to someone losing their life and we have seen in the past that one punch can, in fact, kill someone."
Little information was released about the circumstances.
The senior detective said it seemed as if the victim had an altercation with another man inside the pub which continued onto the street outside.
Several videos have been made available to police already.