The fire service personnel rushed to the spot along with earthmovers to try and rescue the boy, who is believed to be alive, police said.
The rescuers are trying to ascertain the depth to which the child has fallen.
The boy was following his father when he slipped and fell in, police said.
The incident comes close on the heels of the death of a three-year old girl on April 6 after she fell into an abandoned borewell in Villupuram district.
