Greek Police late on Saturday announced that 15 people were arrested after a brief street clash in central Athens during day-long protests and rallies on the grim anniversary of a teen shooting death at the hands of a special police guard in 2008.

Additionally, authorities said 54 were stopped and detained, of which four instances turned into arrests.

The disturbances began at around 8 p.m. at the intersection of Panepistimiou and Benaki, when roughly 400 people detached from a larger march of some 5,000 protesters and clashed with deployed riot police. The latter reportedly used tear gas in reply.

Marches, mobilizations and a vigil where 15-year-old Alexandros Grigoropoulos was shot on the evening of Dec. 6, 2008 were mostly without incident.

Flowers and other objects were left at a monument where Grigoropoulos was shot in 2008.