The incident happened at around 10.20 PM on Sunday when the engagement ceremony of one Mohit was underway at Ganga garden at Khera Road, they said.
When the party was on, six persons, all said to be the invitees and guests, reached the dais and started firing in the air.
"One of the bullets hit the youth, who has been identified as Pankaj, and was rushed to hospital where he was declared brought dead," a senior police official said.
Police identified those who fired in the air, he said, adding they would be arrested soon.