Dehradun, June 06: Three persons including a security guard of the prestigious Lal Bahadur Shastri Academy were shot dead early today at their house in Mussorie, police said. The other two killed were security guard Kartar Singh's son and daughter-in-law, police said. All the three were called out of their house by unidentified persons before being shot dead, police said adding that they died on the spot. The assailants managed to escape from the scene, police said. A manhunt has been launched to track them down. Police said preliminary investigations indicated that the murder was committed due to personal enmity. A family member of Singh's daughter-in-law was said to have been unhappy over her marriage to the security guard's son, they added. Bureau Report