Satpal and his son Raj Kumar were working at the Dera canteen around 7 pm when unknown persons shot in their heads, Khanna SP Satnam Singh said.
Both of them died on the spot, Singh said adding that both belonged to Ahmadgarh.
Though it was yet to be ascertained how many assailants were involved in this incident, the SP said four to five cartridges of .32 bore were found from the spot.
"We are looking for CCTV footage around the crime scene to trace the accused," he said.
A murder case has been registered in this regard, police said, adding security has been beefed up around the areas.