A 23-year-old man was punched in the face and threatened with a hammer as he got out of a car in Co Antrim seaside resort in the early hours of Sunday.
He was approached at around 2.55am by a man in Mark Street, Portrush who punched him "several times" before stealing his phone.
Meanwhile, a second man took car keys from one of his two friends who was still inside the vehicle.
A police spokeswoman said all three of the men in the car "tried to protect themselves in the vehicle" as the two assailants smashed the windows.
She appealed to "anyone who was in the area of Mark Street in and around 2.30am/3.15am and who may have witnessed this incident, or anyone who has any information that could assist with enquiries, to contact police at Coleraine on the non-emergency number 101, quoting reference 431 of 15/12/19".
