A 17-year-old boy was swung at with "something like a large stick" and struck on the shoulder by a group of men while walking through a Northampton Park.
The incident happened sometime between 9pm and 9.45pm on Tuesday (August 22) in Abington Park.
The 17-year-old was walking with three friends when they heard whistling behind them. On turning around, they saw a group of men, one of whom swung something like a large stick, which caught the boy on the shoulder.
The offenders are all described as white men in their early 20s. One was wearing red tracksuit bottoms with white stripes and had a small red or brown bike, one had a white mountain bike and was wearing a graduated grey top, one was wearing a grey hooded top and blue body warmer and another was wearing a grey top.
Anyone who has information should contact police on 101 or Crimestoppers anonymously on 0800 555 111 and quote incident number incident number 17000360410.