A man is seriously ill in hospital after being assaulted in east Belfast in the early hours of Tuesday.
Police have been searching the Connsbrook Avenue area
Four men have been arrested and are being questioned about the attack which happened in the Connsbrook Avenue area at about 0040 BST.
It is understood the victim, who is not from the area, had been invited to a party at a house in the street after a night out in the city centre.
Police are still investigating the circumstances surrounding the attack.
However, it is understood there had been a row inside the house.
The victim was taken to the Royal Victoria Hospital.
Detectives have been using a sniffer dog to search an area off Connsbrook Avenue.
Police have appealed for anyone who witnessed the attack or has any information about it to contact them at Strandtown PSNI station.
Alliance assembly member Naomi Long said the incident was "horrific".
"I hope that the victim makes a swift and full recovery and I would call on anyone with information on the incident to contact police immediately," she said.
Ulster Unionist Michael Copeland said: "This is a particularly regrettable incident and I hope the young man makes a full recovery.
"Incidents such as this are an all too frequent occurrence on our streets."