Murder probe after Derby city centre stabbing
A man who was found with stab wounds in Derby city centre and who later died in hospital was murdered, police say.
The 22-year-old was attacked in St Peters Street at about 20:30 GMT on Tuesday.
Four men, aged 15, 16, 17 and 22, have since been arrested in connection with his death and remain in police custody.
Derbyshire Police set up a large cordon which included East Street and St Peters Street and told the public to expect "disruption to businesses".
Det Ch Insp Dave Cox who is leading the investigation said: "We do have a number of people in custody, however, this does not mean this is the end of the investigation.
"We are still appealing for people who have any information that may help our enquiries to come forward."
Officers handed notices to pedestrians thanking them for their co-operation while forensic teams worked.
The leaflet said it was "imperative" that a "sterile" area was protected so evidence can be preserved.
Some of the cordons have now been lifted but officers have said some will remain in place for most of the day.