The incident took place around 8 AM when Kailash Gupta (40) and son Rajan were heading towards their home in east Delhi's Harsh Vihar area on their motorcycle.
A car intercepted their motorbike and opened fire on them, a police official said.
The first few bullets missed the father-son duo and hit a tea-seller near a mazar in the area and two passers-by.
By the time locals gathered around and called up police, the accused managed to escape, he said.
In preliminary investigation, he said, it appears to be a case of personal enmity.
A case has been registered and efforts are on to nab the accused, the official added.