Last night's incident was captured by the CCTV camera installed in the petrol pump premises, they added.
Raju Kumar, who was a resident of Mayfield Garden in Sector-51, went at petrol pump to give Diwali gift to its owner, police said.
When Raju entered the petrol pump premises in his car, four persons on two bikes came in the petrol pump and open fire at Raju the minute he left his vehicle, an eye witness said.
They relentlessly fired six rounds of bullets at Raju until he died on the spot, he added.
"We had given written complaint to Gurgaon police at Sadar Police Station after sensing life threat to Raju but police didn't take the matter seriously which resulted in his murder," said Sunil Kumar, deceased younger brother.
Prima facie it appears to be a case of personal animosity and gang war, police said.
A case of murder against four unidentified persons has been registered in Gurgaon Sector-5 police station.
No arrests have been made so far, he said.
