Ram Babu Gupta, district president of the Hindu Yuva Vahini, was shot dead by unidentified assailants late Sunday night while he was returning from his hotel in Tanda, 470 km from here.
As news of the killing spread, his supporters took to the streets, torching vehicles, attacking policemen and damaging government and other properties.
Police personnel who reached the crime scene were chased away and the station house officer was thrashed. Many vehicles, including a police jeep, were torched, forcing the police to fire in the air.
Officials said the situation was brought under control early Monday morning and efforts were on to pacify the irate mobs that had gathered at the house of the slain politician.
"The supporters of the deceased have gone on the rampage. We are trying to bring the situation under control," said Superintendent of Police D.P. Srivastava.