Police are tracing the source of the emailNEW DELHI: A bomb threat email sent to the headquarters of Indian Space Research Organisation on Thursday prompted a major security operation, police told news agency PTI.Officers, along with the Bomb Detection and Disposal Squad (BDDS) and dog squad, searched the premises after all staff were evacuated as a precaution. Nothing suspicious was found, and the threat was later declared a hoax. Police are now tracing the source of the email, with further investigations underway.