The 16-year-olds, who were in the Bavarian capital on a school trip after finishing their exams, could have easily killed one of their victims, state prosecutor Laurent Lafleur told Focus magazine.

He said one of their victims was a disabled man from Macedonia who the trio beat until he lost consciousness.

One of the attackers then took a run up and kicked his head which was flopping over the edge of a park bench.

“One can only speak of good luck that the man did not suffer a broken neck and die,” said Lafleur.

The students went on to attack two more men, seriously injuring one man who they beat to the ground, and then singling out a young man who they repeatedly punched.

Focus also reports that one of the Swiss students once attacked a man in the metro in Zurich, breaking his nose. He was caught on security camera and sentenced to 10 days social work and made to pay 150 Swiss Francs in compensation.

The president of their school in Küsnacht, Max Heberlein said he could offer no explanation as to why the trio had turned so violent, saying there had been no instances of fighting in the school. He said one of the three had sometimes arrived late or not done his homework, but that he knew of no reason to think they would carry out such an attack.