The victim, Rishipal, was an eyewitness in the 2012 murder of Pradeep, who is the brother of the chairman of local municipality Surender.
According to Superintendent of Police, Rural, Vinit Bhatnagar, 35-year-old Rishipal was sitting in a shop when five persons came and opened fire on him last evening.
Rishipal died on the spot while the shopkeeper, Vipin, was rushed to hospital in serious condition.
Police said Rishipal was receiving threats in connection with the case. Police security provided to him was withdrawn three days ago.
Police have started an operation to nab the assailants. Additional police has been deployed in the area.