The incident took place when Ashok along with his brother Sunil Kumar, 48, had gone to the market and their motorcycle hit a woman near the Sham Palace where a marriage party was going on.
SHO of the area Brij Mohan, who recorded the statement of Sunil Kumar, said the two brothers were going to the market when their two-wheeler hit a woman who was going along with a group.
"Soon after the incident, a group came from inside the marriage party and started beating the brothers. Somehow, Sunil managed to flee from the spot, but the mob caught Ashok and beat him up to death," the SHO said.
He said the four persons, all from the marriage party, were arrested and a case section 302 of the IPC had been registered under.
"We are looking for 17 persons who are also involved in beating up the victim," Brij Mohan said.
Those arrested have been identified as Ashish Kumar of Manimajra, Manga Masi of Amritsar, Amandeep and Abhishek, both residents of Esanagri.