Three teenagers were attacked by five men as they walked through a Northampton park.
The assault happened between 8.45pm and 9pm on Saturday (March 3) between the boating lake and main lake in Abington Park.
One of the victims suffered minor injuries and they ran off in the direction of Wellingborough Road.
A Northamptonshire Police spokesperson said: "The offenders were all white and wearing tracksuits and described as being Eastern European."
Anyone with information should call Northamptonshire Police on 101 or Crimestoppers, in confidence, on 0800 555111.