A person was stabbed near Eastbourne seafront this afternoon (Thursday).
An air ambulance joined other emergency services including firearms officers on a beach off Royal Parade, near The Redoubt, at around 4pm.
Police said officers were called to Cambridge Road after reports an 18-year-old man had suffered several stab wounds.
He was taken by air ambulance to Royal Sussex County Hospital in Brighton, police said.
No arrests have been made at this stage, but the investigation is ongoing.
Anyone with information can contact the police online or by calling 101, quoting serial 995 of 03/10.
Royal Parade was reportedly blocked by police cars for some time.