Tamluk, Aug. 5: A bomb that a 17-year-old boy had made exploded in his school bag today when he was taking it out to show his friends after tuitions.

Biswanath Bakshi, a Class XI student who studies science, seriously injured his right eye and right arm. Three of his friends suffered minor injuries.

The circle inspector of Mahishadal, East Midnapore, Shekhar Roy, said Biswanath had made the bomb to surprise his classmates after a football match, where he was supposed to go after the coaching class.