A class 8 student of a government school in South Delhi's Saket attacked his teacher with an iron rod inside the classroom today, the police said.
The teacher, Shyam Sundar, was seriously injured.
In the morning, Mr Sundar, an English teacher, spotted an iron rod and a notebook inside the student's bag while going through it.
However, when he threatened to inform his parents about the rod and tried to take it away, the student attacked him with the same rod.
The 12-year-old boy managed to climb the boundary wall of the school and escaped soon after.
The police reached the spot after being informed around 9:30am and found the teacher lying in a pool of blood, said officials. He was immediately rushed to the All India Institute for Medical Sciences.
It was not immediately clear why the student was carrying the rod to the school, in the first place.
More details are awaited.
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