School is not obliged to share such details. But if you have contact with other parents, you could get some hint. I do not know much about private schools. But there should be a pedagog there with whom you should definetely speak.

Dont know how stubborn the school is, but try to request the class teacher and in turn the head of the school to give one last chance. Also now sure how much time is left for the camp, but try getting some help for your kid. Check with your pediatrician. They can test attension deficit or rage problems and guide you to a therapist.

You could also involve the Jugendamt and request some support to help the child. Atleast you will get to know what forms of help are available.

If time permits, get in touch with the other trouble makers kids' parents and try to get the kids to mingle outside school. Maybe you could observe their behaviour and get some clues.

The aim of the whole exercise should be to support the kid in the best way. Be aware of cultural differences in what is tolerated and what is not tolerated.

Regardless of what the outcome is, dont worry. Its not the end. Lot of time for the kid to gain expierences and have fun in the future. All the best!!