A teenage boy has sustained a “potentially life-threatening head injury” during an assault in Londonderry, according to police.
Officers found the 17-year-old lying unconscious on the ground after they were alerted to an altercation between two people on Butcher Street.
The altercation was witnessed by city centre CCTV operators just after 02:25 GMT on Sunday.
They reported it to the Police Service of Northern Ireland (PSNI) but when officers arrived the other male involved in the incident had left the scene.
The injured teenager remains in hospital and the PSNI has appealed for witnesses to help the investigation.
“We know that a number of people were in the area at the time and would appeal to anyone who witnessed this shocking incident to come forward,” said Det Insp Connolly.