Five teenagers were seriously injured in stabbings at a Halloween party in Chandler's Ford, Hampshire, on Saturday night. Police were called to an address on Park Road shortly after 22:30 GMT. The victims were three boys aged 16 and two aged 17, all taken to hospital.
Hampshire Police said an unknown group gained entry to the party before the stabbings occurred. Eyewitnesses reported ambulances and an air ambulance attended the scene. One witness saw someone running from the house shouting that he had been stabbed and that two people were chasing him.
A police cordon remained in place on Sunday as the investigation continued. Senior investigating officer Det Ch Insp Elizabeth Pirie said police recognised the incident's impact on local residents. Hampshire Police appealed for witnesses and anyone with information to contact them.