Police were called to reports of an assault at a premises in Kings Road Arches, Brighton, at around 9pm on Wednesday, 7 August.
In a separate matter during the same call-out, officers removed a 17-year-old girl from the premises. She was subsequently arrested on suspicion of assaulting an emergency worker.
The teenager was taken into police custody and later released on bail while further enquiries continue.
Sussex Police are appealing for anyone with information about the assault to come forward. Witnesses can contact police online or by calling 101, quoting serial 1478 of 07/08.
