A man’s jaw was shattered in an attack in Rotherham Valley Country Park after he was punched in the face and knocked to the ground.
The 34-year-old victim, an Asian man, was targeted in the north west corner of the park between the lake and a railway bridge that leads to Beighton.
His attacker was white, around 5ft 9ins tall, slim, clean shaven and wearing a balaclava or face covering.
He was with a small group of people before the attack, and ran off into woodland afterwards.
Police searched the park but were unable to find the culprit.
They described the assault as ‘serious’ and said the victim suffered multiple fractures of the jaw.
Witnesses or anyone with information should call South Yorkshire Police on 101, or Crimestoppers anonymously on 0800 555111.