Five teenagers have been arrested after a 17-year-old boy was stabbed at what police believe was a flat party.
Two other people, a 17-year-old boy and a 16-year-old girl, were also injured in the incident.
Emergency services were called after the incident at an address in Hounds Gate, Nottingham, shortly after 11.40pm on Friday, Nottinghamshire Police said.
The stab victim was taken to hospital with serious but not life-threatening injuries.
An 18-year-old man and four boys aged 17 have been arrested and remain in police custody, the force said.
Road closures remain in place on Hounds Gate, Maid Marian Way, Standard Hill and Lenton Road as investigations continue.
Nottingham Castle said on Facebook it was “temporarily closed” on Saturday due to the closures.
Detective Inspector Chris Berryman said: “We believe this incident happened during a party at a flat and we are working to understand events in the moments before, during and after what happened.
“We particularly want to hear from anyone who was inside the flat, or who witnessed people running from the scene shortly afterwards.
“Drivers with dashcam footage are also asked to get in touch if they witnessed any part of this disturbance.
“This kind of violence is utterly unacceptable, and we will do whatever it takes to bring the person or people responsible for these injuries to justice.”
Superintendent Kathryn Craner said: “At present, there is nothing to suggest that this incident is linked to those earlier in the week.
“We will however keep an open mind while the events of last night are meticulously investigated.
“We will continue to maintain a high and visible presence in the city to provide reassurance and speak with anyone who has concerns.”
