A man needed "significant treatment" in hospital after being attacked by a gang of youths and receiving serious facial injuries.
The incident happened around 10pm on Friday in Dick Crescent, Burntisland, Fife.
Police said a 33-year-old man was approached by a group of young men and women and assaulted.
He was taken to the Victoria Hospital in Kirkcaldy and later released.
Officers believe the attack may have been filmed on mobile phones.
Detective Sergeant Samantha Davidson said: "This man has sustained serious facial injuries, which have required significant treatment.
"We are keen to speak to anyone who witnessed the incident or who was in the Dick Crescent area on the evening of Friday May 26.
"We are particularly eager to speak to persons who may have recorded the incident on mobile devices.
"Anyone who can assist our inquiries is urged to contact us as soon as possible.
"Those with information are asked to contact officers at Kirkcaldy CID on 101, quoting incident number 5238 of May 26, or anonymously via Crimestoppers on 0800 555 111."