The incident occurred yesterday afternoon when Mahavir Yadav's motorcycle hit the car leaving some scratch marks on it, a police official said.
On seeing scratch marks on the car, its owner Vikas, who was driving it, started to abuse Yadav which later turned into a brawl, he said.
Vikas called his brother Ravi who reached there and suddenly pulled out a gun and fired four rounds at Yadav, the officer said.
Yadav died on the spot, while Vikas also received a bullet injury as he to tired to stop Ravi from pulling the trigger, police said.
"Yadav was a resident of Jhajrola village and ran a clinic at Ghumarpur village near Pataudi," he said.