A man was seriously injured in an attack in the centre of Brighton in the early hours of this morning (Friday 26 October).
The man, who is in his thirties, was taken to the Royal Sussex County Hospital in Brighton with life-threatening head injuries.
A scene guard remains in the area while officers carry out forensic examinations and speak to locals.
Detective Inspector Miles Ockwell, from Brighton and Hove CID, said: “We are in the early stages of the investigation and would appeal to anyone who has not yet spoken to officers to please come forward.
“Did you see or hear any suspicious activity between 11.30pm (25 October) and 12.30am (26 October) in the area of St James’s Street, the New Steine or Lower Rock Gardens?
“We believe the suspects may have fled the scene of the attack on a motorcycle.”
Anyone with information about the attack is asked to call Sussex Police on 101 or the independent charity Crimestoppers anonymously on 0800 555111.