In a shocking incident, an engineering student, spurned in love, stabbed to death his classmate and her sister here on Tuesday, police said.Angry over his proposal being rejected, Amit Singh barged into the house of Srilekha and attacked her with knife. As her sister Yamini tried to save her, Amit also stabbed her, police said.The profusely bleeding sisters were taken to a hospital, where both succumbed to their injuries.Police have launched a hunt for Amit, who escaped after the attack in Mohan Nagar area in Chaitanyapuri.A final year engineering student in a private school here, Amit had been pestering Srilekha for some time to accept his proposal but met no success.On Tuesday, he came to her house and picked up an argument. He then whipped out a knife and stabbed her. As her elder sister Yamini tried to save her, Amit also attacked her.The girls' parents were not at home when the incident occurred. The family hailing from Shadnagar in Mahabubnagar district of Telangana was settled here.