A 21-year-old man remains in a critical condition in hospital after being stabbed in a city centre street, police have said.
The victim was found near a Primark store in Long Row, Nottingham, with what police described as a puncture wound to his body at around 1.45am on Sunday.
An extensive search of the area has now taken place while detectives are also viewing CCTV footage as they attempt to identify the offender, said Nottinghamshire Police.
Detective Inspector Leigh Sanders said: "We believe the altercation took place near to where, and not long before, the victim was found.
"It is also possible that there were a number of people involved."
Appealing for witnesses, the senior officer added: "There is a man who is gravely ill in hospital.
"The area would have been busy at the time of the incident, as people would have been leaving pubs and clubs.
"There are people out there who know who did this and it is only a matter of time before we find out."
DI Sanders also appealed for anyone who knows someone who has been behaving suspiciously since Saturday night to contact detectives.
Anyone with information is asked to contact Nottinghamshire Police on 101 or the Crimestoppers service on 0800 555 111.