A constable in Tamil Nadu Police's special battalion force shot his girlfriend dead and killed himself later by using his service revolver after celebrating her birthday in Villupuram district of the state in the wee hours of Wednesday. 

The deceased have been identified as S Saraswathi, a 19-year-old  from Anniyur village in Villupuram district who was studying in a private medical college in Chennai and K Karthikeyan, 24, a native of Sathyamangalam of Erode district who was serving as an armed reserve constable attached to Vellore battalion, according to a report.

Karthikeyan had met Saraswathi on Facebook four years ago and eventually fell in love. He started visiting her house after getting her parents' nod for marriage, the report said.

However, the duo had some issue a month ago when Karthikeyan had scolded Saraswathi for speaking to her male classmates.

On Tuesday, Karthikeyan along with his friends visited Saraswathi at her native village to celebrate her birthday together. But the duo entered into an argument at 2 am over an issue. In a feat of anger, Karthikeyan pulled his service pistol and opened fire on Saraswathi. Moments later he killed himself by firing at his head.

Villupuram SP S Jayakumar along with other officials visited the spot.

Police have sent the bodies to the Government Villupuram Medical College for a post-mortem examination.

An investigation is on.