A teenager was shot in the head and killed in Buenos Aires early Friday after a Boca Juniors "supporters' day" erupted into violence, police and witnesses said.
The young victim, who was named as Rafael Ruiz, 19, was on a train from the festivities with hundreds of other fans when they were shot at from a van, witnesses said.
He was hit in the head and chest and died on the way to hospital. Police were investigating whether supporters from another club were to blame or if it was a rival Boca Juniors gang.
Thousands of supporters of Boca, decked out in the club's famous blue-and-yellow jersey, had gathered Thursday night in the center of the Argentine capital.
Shops were attacked when the mood turned sour and supporters clashed with police. Twenty-two people were arrested.