Police said the arrested were identified as Gokul (17), Sudhan (16) both 10th standard students of the same locality and Sriram (16), employed in a private firm.
A preliminary inquiry revealed that the trio wanted to make money to lead a lavish lifestyle and kidnapped the boy while he was playing with his friends in order to procure a ranson of Rs 5 lakh.
As soon as they made the demand of the boy's parents, the latter called the police. After this, they killed the boy.
Police said they caught the assailants on Thursday night after a continuous search based on clues given by the boys and girls who were playing with the murdered child.
Aravind, a sixth standard student and son of a business executive of a city-based corporate hospital, was playing with his friends near his home at Virugambakkam when he was abducted on Tuesday night.
A passer-by noticed the body lying in a bush at Sathyamoorthy Nagar area of Virugambakkam and informed the police.
