I dont know why people are so shocked, beating in school in Pakistan is considered normal. and it happens also good middle class pvt schools.
Punishing him wont create any change unless the mentality of the society isnt changed. hitting a child is really bad for confidence and character development, and this is not some hockey pokey liberal theory, I speak to you with personal experience, I was slapped on multiple occasions in school, specially by a teacher whose class I attended for only 3 weeks, this caused a real confidence issue with me during my whole student life, it was only latter when I recognized the problem and the cause of it, I was able to overcome this. And I still curse that teacher from the bottom of my heart!