Head Constable Vijay Prathap Singh allegedly opened fire from his 9mm carbine killing Assistant Sub-Inspector Ganesan and head constables Subburaj and Mohan Singh inside the barracks where all of them were taking rest early in the morning, said the police.
According to the police, Assistant Sub-Inspector Prathap Singh and head constable Govardhan Singh sustained major injuries and are being treated at a hospital.
The reason for the attack are still not known, said the police.
The accused, head constable, Vijay Prathap Singh has been arrested and is being questioned.
Police said there were at least 50 more CISF personnel during the incident.