One of the accused was also arrested after a CCTV footage of the incident went viral on social media.
Dileep (26), and two of his friends had on Friday came to a restaurant in Karnalganj when an altercation broke out with some persons there. Soon after, they assaulted Dileep with sticks and batons, leaving him grievously injured.
On the basis of a complaint lodged by Dileep's brother, an FIR was registered against three unidentified accused, SSP Akash Kulhari said.
The restaurant owner Amit Upadhyay was arrested as he was familiar with the accused, Singh, and did not inform the police about the incident.
The body has been sent for post mortem and further probe into the matter is on, the senior official said.