A 17-year-old boy was arrested and held in custody on suspicion of shooting dead an Indian university student in Salford, outside Manchester.
Twenty-three-year-old Anuj Bidve, a postgraduate electronics student at Lancaster University, was shot dead in Salford in the early hours of Boxing Day, police said.
Bidve was visiting Manchester with a group of nine friends for a short break over the Christmas holidays.
The group were walking from their hotel in Salford towards Manchester city centre in the early hours when they were stopped by a man who began talking to Bidve before pulling out a handgun and shooting him at close range.
Bidve collapsed to the ground and was rushed to hospital where he was later pronounced dead. His family in India have been informed.
Police and armed response units were called to Ordsall Lane following reports of a shooting near a local McDonald's restaurant.
Greater Manchester Police said it was a shocking incident and that the attack was unprovoked.
"This appears to be an unprovoked attack and we can't establish a motive. We are investigating every possible aspect and are in the early stages of the investigation but we are not ruling anything out," said Chief Superintendent Kevin Mulligan, divisional commander for Salford.
The gunman who fled the scene was described as a slim white man in his twenties, and was said to be wearing a grey top. A second man who was with him was of a heavier build and wearing a black jacket.
"There is bound to be anxiety in the community about this but we have got an increased police presence in the area, we have got a thorough investigation going on," said Mulligan.
"I don't want to detract from the seriousness of this incident, but violent crime in the city is down overall."
Police have not ruled out the possibility that it was a racially motivated attack.
They are witnesses to come forward. Anyone with information is asked to call the incident room on 0161 856 5448 or the independent charity Crimestoppers, anonymously, on 0800 555 111.