A man was seriously injured following a vicious assault in Letterkenny on Sunday evening.
The man, who remains in hospital, was attacked on the High Road, around 11.20pm.
Passing Gardai noticed a number of people had gathered in the area and an injured man lying on the footpath.
Gardai want to speak to a man who may know more about the incident.
He is described as having a dark complexion, about 5ft 6 inches tall, of thin build and in his late teens.
He has short dark hair on the back and sides but curly on top and he had no facial hair and it is understood he was wearing a black t-shirt.
Anybody with any information is asked to contact Letterkenny Gardai on 0749167100.