A man suffered a "nasty head injury" after he was assaulted in a car park.
At about 7pm on Friday (11 April) officers were called to Luxford Field car park in High Street, Uckfield, to a call about a fight there.
When officers arrived they found a 35-year-old man from Uckfield had suffered a cut head. He was taken to hospital for treatment.
A 43-year-old woman was arrested on suspicion of assault and questioned before being released on bail while officers carry out further inquiries.
PC Jess Dixon said: "It is unclear at this stage exactly what happened in the car park but at least one person has suffered a nasty head injury.
"I'd like to speak to anyone who was in the car park or nearby at about 7pm on Friday and might have seen what happened or who knows who was involved.
"If you know anything at all please contact us."
Anyone with information should call 101 quoting serial 1273 of 11/4, email firstname.lastname@example.org or call the independent charity Crimestoppers anonymously on 0800 555111.