He said that the shooting had taken place at around 10.00 pm in Gajanayakagama Grama Sevaka Division over a family dispute.
The boy who was critically injured in the event was admitted to the Weerakeitya Hospital and then Tangalle Hospital for further treatment, where he succumbed to his injuries.
However, the person who had shot the child has fled the area and three others involved in the incident has been arrested, the SSP said.
Several police teams have been deployed to apprehend the suspect who is evading arrest.
Further investigations into the matter are carried out by the Weeraketiya Police.