Police was informed around 3.25 PM about a boy crying for help after he fell into a drain in Chhawla area, said a senior police officer.
He was rescued and rushed to a hospital where he was declared dead, he added.
He was identified as Mandeep. During investigation, it emerged that he had left his home along with three-four of his friends in the morning.
However, when police reached there, his friends were not present at the spot.
Mandeep's chest has a puncture wound that could have been sustained due to a compass or a thorn, said the officer.
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"A post-mortem examination will clear the picture. The behaviour of his friends appears to be suspicious," he added.
A murder case has been registered since there appears to be some sort of foul play, police said.
Police have detained his friends for questioning. They are being probed whether a quarrel took place between the friends and if in a fit of rage they attacked or pushed him into the drain, he said.
Mandeep and his friends are students of Veda Vyasa DAV Public School. Mandeep's father is a cab driver.