A 27-year-old security guard was allegedly stabbed to death by an unidentified person in northeast Delhi's Khajuri Chowk area, police said on Friday. Varun, the victim, was a resident of Sonia Vihar, they said. The alleged stabbing took place around 5.20 pm on Thursday. Varun was on his way to visit his sister in Garhi Mendu and had come to Khajuri Chowk to buy fruits, the police said.