Harkirat Singh, grandson of Punjab's late chief minister Beant Singh, allegedly shot himself dead in his house here on Sunday afternoon, police said.With a gun-shot injury in his head, Harkirat was rushed to the Post-Graduate Institute of Medical Education and Research (PGIMER) here where doctors pronounced him dead, said Neeraj Sarna, the officer in charge of Sector 3 police station."We are investigating the reason behind the incident," Sarna said.Chandigarh Police said they were not ruling out suicide.Harkirat was staying in the official bungalow allotted to Beant Singh's family in Sector 5 here.The family continues to enjoy high-level security provided by Punjab Police and para-military forces.Beant Singh, who was credited with restoring normalcy in Punjab in early 1990s after many years of terrorism, was assassinated on August 31, 1995, by a human bomb at the Punjab Secretariat Complex here.