The youth attacked Yogesh Jain, 55, a property dealer. He also attacked with a stick Poonam, 50, the girl's mother. The couple were in their house in Jyoti Nagar in east Delhi at that time, police said.
The young man has since fled and is now untraceable, police said.
Yogesh Jain was hit by the bullet fired by the man in the abdomen.
The attack occurred around 10 a.m., soon after the man proposed to the elder daughter of the Jains, and found his proposal turned down by the girl.
Police said the man scuffled with the girl soon after she rejected his proposal. The girl managed to escape, and the man turned his ire on her parents.
The attacker, a resident of Shahdara, was pursuing the girl for several months. He became acquainted with her while she was in school. The girl has since joined Delhi University.
Naresh, a neighbour of the Jains, said he heard a bullet shot followed by screams, and rushed to the first floor of the multi-storey building where the family lived.
"When I reached the spot, I found Jain in a pool of blood. His wife was unconscious, and the daughters were in shock, crying. The attacker had fled," Naresh told IANS.
"We informed the police and took Yogesh and Poonam to GTB (Guru Tegh Bahadur) Hospital," Naresh said.
Doctors said the condition of both parents was critical.
Another neighbour said the Jain family had only recently shifted to this building.
A senior police officer said a hunt has been launched to nab the attacker, and added that the family had not lodged any complaint with them about the trouble their daughter faced.
--IANS (Posted on 08-09-2013)