A 21-year-old man who was stabbed in the early hours of Sunday morning in Nottingham remains in a critical condition in hospital.
The man was found near the Primark store in Long Row with a puncture wound to his body at around 1:45am yesterday.
An extensive search of the area has taken place and detectives are viewing hours of CCTV footage covering the city centre.
Detective Inspector Leigh Sanders, said: "We believe the altercation took place near to where, and not long before, the victim was found.
"It is possible that there were a number of people involved."
Nottinghamshire Police are appealing for witnesses and information in relation to the assault.
An investigation is underway after a man was found injured in Nottingham city centre.
The 21-year-old was found in Long Row at 01.45 this morning (Sunday 11 November 2012). Police say he had been violently assaulted.
The man is in a critical condition at the Queen's Medical Centre.
Long Row has been closed from its junction with High Street to the Council House, while forensic examinations are carried out.
Nottinghamshire Police want to speak to anyone who witnessed the assault.