Singh has taken voluntary retirement and was allegedly having an "illicit" relation with a woman.
On Wednesday, the court asked Singh to settle the matter with his wife and fixed the matter for December 15.
When Singh approached his wife for settlement, she did not agree and a heated argument followed.
In a fit of rage, Singh fired 4 rounds at Kaur and also shot at his nephew and mother when they tried to intervene.
Later, he also tried to shoot self but was overpowered by people, police said.
Police have registered a case against the accused and arrested him.
Both have a daughter, who is married and settled abroad.