A 22-year-old man has suffered serious stab wounds to his back and side, police have said.
Officers arrested a 21-year-old man on suspicion of attempted murder following the incident in Downpatrick, Co Down, between 3.30am and 4am on Sunday.
The stabbing took place in the Ardilea Park area of the town.
The PSNI said officers were called to a property in the Killough Road area where they found the victim.
His injuries were described as not life-threatening. The PSNI said the knife used in the attack may have been discarded and they urged the public to be vigilant.