An argument followed between the neighbours and Vineet. Police said Dheeraj allegedly pulled out a country-made pistol and opened fire.
The bullet first hit a wall before striking Saurabh in the head. He was rushed to a hospital, where doctors performed surgery and removed the bullet.
His condition is now stable.Saurabh's father alleged that the accused had an old enmity with their family. Police have registered an FIR against both brothers on charges of attempt to murder and are trying to trace them.
Saurabh, who has been posted with the Rashtrapati Bhavan security for seven years, is married and has a nine-month-old child.