A man has been stabbed to death in a "shockingly violent" city centre brawl which left several other people in hospital.
The 21-year-old, who has not yet been named, was knifed in the neck during a large fight near Deansgate in Manchester.
Several other people were taken to hospital, including a man who had been hit with a glass and two women, aged 19 and 21, who were left unconscious after being punched.
Police were also attacked during the fighting and two officers had to be treated for minor injuries.
A number of men and women were involved in the incident in John Dalton Street in the early hours of Saturday morning.
Four men - two aged 19, one 21 and another 24 - were arrested and are being questioned by police.
Chief Superintendent Emily Higham, of Greater Manchester Police, appealed for anyone who saw what happened to come forward.
"What we were faced with during the early hours of this morning was a large group of men and women fighting in the street," she said.
"Sadly, a 21-year-old man has lost his life. My thoughts go out to his family at this unimaginably painful time.
"We are appealing for anyone who witnessed the fighting to get in touch as soon as possible.
"We believe the fighting started in the Suburbia nightclub and spilled out on to the road, so there is potentially a nightclub full of witnesses who we want to hear from.
"There is currently a scene in place and some road closures in the area.
"I am asking anyone who has any information or concerns to get in touch with police as a matter of urgency.
"The level of violence people were using towards each other and police was shocking and this resulted in the tragic loss of a young man's life.
"We cannot let those responsible get away with this."
Anyone with any information can call the police on 0161 856 4227 or 101 or Crimestoppers anonymously on 0800 555 111.