The three 18-year-olds and one 15-year-old were convicted of attempted murder for attacking a 30-year-old house painter and his co-worker at the German capital’s Lichtenberg U-Bahn station in February.

The victim’s co-worker escaped with minor injuries, but the 30-year-old suffered massive brain trauma during the beating and remains severely injured.

During the trial, prosecutors argued that the accused – all of whom are from immigrant backgrounds – had been motivated by “hate of Germans” and “having fun by committing gratuitous violence against the weak.”

The teens told police that they had been provoked after the man shouted the Nazi salute “Seig Heil” at them, but police dismissed that claim after speaking to witnesses.

Authorities expressed shock when the incident took place, with Berlin’s interior weighing in with strong condemnation. They also said they were surprised no bystanders stepped in to protect the helpless victim.

The incident was one of several recent attacks at public transportation facilities that left the German public angry and authorities struggling to improve security.

In a similar incident in April, a German teen was sentenced to nearly three years in prison for attacking a man at Berlin’s Friedrichstraße U-Bahn station. In that case, a witness did step in to stop the violence.

The Local/DAPD/mdm