Footage from a security camera at Rohtak's Skytech mall shows the men attacking the guard, identified as Sunil Kumar, in the early hours of Thursday.
The police have identified one of the attackers as Dheeraj and arrested him. He is seen hitting Mr Kumar with his belt before he is joined by others armed with sticks.
The police are still unclear about what provoked the attack. The group, say the police, had come to an adjoining community centre for a wedding function.
Mr Kumar died in hospital. The police have launched a manhunt to look for the others caught on camera.