Detectives are appealing for witnesses after a man was attacked by up to 10 people on Saturday night.
It was reported that at around 6.35pm the 20-year-old was assaulted by a group of youths on Skegoneill Avenue in Belfast.
He was knocked to the ground and struck with what is believed to have been a hammer. He sustained a suspected fractured wrist and swelling to his head and face as a result of the attack.
A boy (17) was arrested a short time later on suspicion of grievous bodily harm and is currently in custody assisting police with their enquiries.
Det Insp Mark McHaffie is appealing for anyone who was in the area of Skegoneill Avenue or Jellicoe Avenue on Saturday evening and who witnessed the assault to come forward.
Anyone with any information that can assist with the investigation can contact Musgrave Police Station on 101 or Crimestoppers on 0800 555 111.