Emergency services were called to a property in Bath on Saturday night.
Eight teenagers have been arrested on suspicion of murder after a 16-year-old boy was fatally stabbed.
Emergency services were called to an address on Eastfield Avenue, Bath, shortly after 11pm on Saturday following reports of a stabbing, Avon and Somerset Police said.
Members of the public provided the boy with first aid before paramedics arrived, but he could not be saved and died at the scene.
A 35-year-old woman was also stabbed in the incident and attended Royal United Hospital for treatment. She had since been discharged.
Eight people – six boys and two girls aged between 15 and 17 – were arrested on suspicion of murder from a bus on Lansdown Lane at 11.30pm.
They all currently remain in police custody.
A post-mortem examination to determine the cause of the boy’s death will take place in due course, the force added.
Chief Inspector Ronald Lungu, of the Bath Neighbourhood Team, said: “This is a tragic incident and our thoughts this morning are very much with the family of the boy who has died.
“They were informed of what happened as soon as possible and are understandably devastated. Specialist family liaison officers will now be assigned to them to provide them with support and keep them updated.
“Officers arrived at the scene within minutes of the first call being received and an investigation into the incident is already being carried out, led by the Major Crime Investigation Team.
“We’ve identified a number of witnesses and we’ll be taking formal statements from them in due course, but we’re also keen to hear from anyone who was at the address at the time who hasn’t yet spoken to police. If you can help, please call us on 101.
“The community can expect to see a significant police presence in the area today, and for the next few days, while officers and police staff carry out a number of actions including forensic examinations, a review of CCTV footage and house-to-house inquiries.
“There is currently a large cordon in place on Eastfield Avenue while we carry out these inquiries and I’d like to thank those residents whose properties are impacted by this for their patience and understanding.
“I appreciate this is a concerning incident and I’d like to reassure people a thorough inquiry is taking place, however, should anyone have any questions I’d encourage them to make contact with their local neighbourhood policing team, who’ll be carrying out extra patrols in the area.”
Any witnesses, or anyone who has other information which could help the investigation, is asked to phone 101 and provide the call handler with the reference 5223136640.