Former MLA and BSP leader Sarvesh Singh Seepu and another person was on Friday shot dead by unidentified assailants, leading to violence in the district with protestors clashing with police and a man being killed allegedly in police firing.
Six others were injured in the violence.
The tension erupted after 35-year-old Seepu and Narad Rai (40), who came to him for some work, were shot dead by unidentified men in front of his house, police said.
As soon as the news of the murder spread, hundreds of Seepu's supporters attacked Jiyanpur police station and snatched rifles from policemen, indulged in brick-batting and tried to set police station afire, IG law and order, R K Vishwakarma said in Lucknow.
The angry mob also torched two 'Vajra' vehicles and six motorcycles, he said, adding that police had to open fire to control the unruly mob and attempts are being made to control the situation.
Vishwakarma said besides former MLA, two persons were killed and added that it was not confirmed whether one death took place in police firing.
The incident appeared to be fall out of an old enmity, he said, adding that a search operation has been launched in neighbouring Mau, Jaunpur, Ambekdanaragar districts to nab the assailants.
Seepu was a Samajwadi Party MLA from Sagari seat till 2012. He then joined BSP and had contested the last Assembly elections on BSP ticket from Sadar seat here.
Seepu's father Rampyare Singh was a cabinet minister in previous Mulayam Singh Yadav government.