Danish, supporter of the newly elected chairman of Visharadganj Nagar Palika Riyaz Ahmad, opened fire after his oath ceremony in which a boy Mehtab was killed, Senior Superintendent of Police Sanjeev Gupta said.
Danish has been arrested and a double barrel gun has been recovered from him, he said.
Six policemen, including station officer of Visharadganj Rukum Singh, have also been placed under suspension in the wake of the incident, the SSP said after visiting the spot.
Tension prevailed in the area after the incident.
Riyaz, who contested as an independent in the urban local body elections is said to have been backed by the ruling Samajwadi Party.