A man is in hospital with a serious head injury after an attack in Sheffield city centre.
The 18-year-old was set upon on The Moor at 3.30am on Friday.
Another 18-year-old needed hospital treatment for a facial injury following the incident.
A South Yorkshire Police spokeswoman said: “Police are investigating a serious assault in Sheffield city centre, which left an 18-year-old man in hospital with a serious head injury and led to another 18-year-old man receiving hospital treatment for a facial injury.
“Police believe that a number of people were present during the incident and are urging anyone who witnessed the assault, or who has information about the incident, to come forward.”
Call police on 101.