A 27-year-old man suffered a broken arm after he was assaulted in Eastfield Park, Northampton.
The assault happened between 1.40pm and 2pm on Tuesday, February 16, in a wooded area near the pond.
The victim was sitting on a bench when a group of about 12 young people congregated nearby. Someone made a derogatory comment towards the victim and, as he got up to walk away, he was attacked from behind by one of the men from the group.
He tried to run away but tripped and fell, and was punched and kicked by the offender, sustaining cuts to his hands and face and a broken arm.
The group then headed out of the park in the direction of the Eastfield estate.
The offender is described as white, about 5ft 11in, with a slim build, aged 22 to 25 years-old and with a local accent. He had blonde/light brown hair and was wearing jeans and a light brown jacket.
A couple of people in the group had bull terrier type dogs with them and it is believed there were one or two women or girls in the group.
Officers are appealing for witnesses and anyone with information is asked to call Northamptonshire Police on 101. Alternatively, they can call independent charity Crimestoppers anonymously on 0800 555111.