Police said that the shooting had taken place in Hageby, a usually quiet residential area of Norrköping, in south east Sweden. They were called to the scene after the man’s screams were heard by neighbours.
Officers told the TT news agency that the teenager had been found “outdoors” at around 3am and had been taken to hospital for treatment.
It was not immediately clear how badly injured the young man was.
“He is not entirely unknown to us,” said Jan Fryksén, a duty officer for the region’s police force.
Neighbours are being interviewed by police, while sniffer dogs have been searching the area, Sweden’s Aftonbladet newspaper reported. Forensic teams are also examining the scene of the shooting.
No one has been arrested.
Norrköping is a former industrial city around 160 kilometres south of the Swedish capital. It is Sweden’s eight largest municipality.