Police arrested a teenager within minutes of the incident in Milton Street in the city centre at around 1.15pm today (Monday 12 October). The 17-year-old remains in custody and is being questioned on suspicion of murder.
Enquiries are ongoing to establish how many people may have been involved in the incident and detectives are urging witnesses to come forward.
Milton Street has been closed, between Shakespeare Street and Lower Parliament Street, while officers dealt with the incident.
Detective Inspector Steve Wragg said: “Our thoughts are with the family and friends of this young man, who has sadly died.
“It is a tragic incident that has sadly happened in broad daylight and in front of shoppers in the city centre.
“We have now launched a murder investigation and while it is very early in the investigation we have a team of detectives who will be working tirelessly to establish what happened and who is responsible.
“Nottinghamshire Police and its partners work incredibly hard to reduce violence, but this tragic incident is a reminder that just one offence has huge impacts not only for the victims but their families, friends and communities.
“That is why I am calling on anyone who may have witnessed this tragic incident to come forward as soon as possible and help this young man’s family get justice.
“I am also asking for anyone who has any information on who may have been involved in the incident in some way to give us a call. If anyone notices a friend or family member acting differently and they suspect they may know something, please get in touch.”
Anyone with information is urged to contact Nottinghamshire Police on 101, quoting incident number 304