The teenager was on his way into the city centre to meet with friends when he became embroiled in an argument with other youths at around 6pm, the Passauer Neue Presse (PNP) reports.
The argument spiralled into physical conflict and the teenager was beaten to the floor where he lay unconscious.
The PNP reports that it took some time before emergency services were notified about the incident, despite the fact that many people bore witness to the crime.
When police did arrive, the other people involved in the fight fled. Six suspects were subsequently arrested as part of a wide-scale search.
A medic attempted to reanimate the youth. He was then brought to a hospital and died roughly an hour and a half later.
The suspects are aged between 14 and 25 and are of German, Polish and Tunisian heritage. On Tuesday they were still being held in custody.
It is still unclear why the fight broke out. Prosecutors say though that the victims and his attackers knew one another.