The deceased was identified as Ashish, a resident of Bhim Nagar Balmiki Colony.
According to the police, the incident occurred at around 12.30 a.m. when the victim was at the event with his friends.
The assailants then called the victim outside and shot him dead, the police added.
Upon receiving information, the police reached the spot and rushed the victim to a nearby hospital but he was declared brought dead.
The body has been sent for post-mortem.
“The reason behind the incident is yet to be known but preliminary probe suggest that some old enmity could be a reason reason behind the killing. Police are probing the matter,” Subhash Boken, spokesperson of the Gurugram Police, said.