In a swift action, police arrested the trio late last night, hours after the murder came to light.
According to police, the girl, a plus one student from Periyanmalai village, was missing after she left for school yesterday morning.
Her body was found by her father in a gunny bag in a ground near the village.
A special police team formed by Namakkal Superintendent of Police S R Senthilkumar investigated and nabbed 20-year old Dilip Kumar and his friends -- a 17-year old student and Santosh.