A woman suffered head and chest injuries after being attacked in the street.
The 47-year-old victim was walking with a male friend in Wellington Place, Hastings, when she was assaulted by a young woman.
A passer-by and the driver of a silver metallic 4x4 stopped to help the victim after the attack at about 11.15pm on Friday.
PC Daniel Moss said: "We would like to speak to the person from the silver 4x4 and the other person who helped the victim to see what they can tell us about what happened.
"Did you or a friend of yours witness this incident? If so please contact us."
The attacker, who was with a group of youths, was in her teens and of Afro-Caribbean descent. She was slim, athletic build and had her dark afro-type hair tied back.
She was wearing a shiny blue hooded waist length jacket, blue jeans and boots.
A 16-year-old woman from Hastings was arrested on suspicion of common assault. She was questioned before being released on bail until March 9.