Bullying and beaten up Inside school premises

My Son was bul**** at school he got beaten by 5 learners,he is doing Grade 2 and those learners are doing grade 5. They went to his class and beat him up and is nit for the 1st time, now I go to school to seek answers as to how it happened and enquiring about his safety. Principal Pootgieter threatens to call the security, how am I the bad person when my son is the one that got bul****. The "best thing" they did was to give those learners warning and proudly saying if nothing is done I should go to the district.