In Dakshin Tola area in Mau district, police used force when a large number of people gathered outside a polling station indulged in unruly behaviour. Unconfirmed reports said six persons were injured in the firing.
Police also used force in Mahaveer Akhara hamlet in Rasra area in Ballia district after some local residents indulged in slogan shouting.
"Polling started at 7 AM and in the first four hours 19 per cent polling was registered in 59 seats spread over 9 districts amid tight security arrangements," Election Commission sources said here.
Maximum 28 per cent voting was registered in Maharajganj assembly seat while a minimum of 13 per cent was registered at Tamkuhiraj, they said.
Among districts, maximum 10 per cent polling was registered in Ballia and Deoria districts and minimum 4 per cent in Ghazipur.
There were reports of voters boycotting polls at Bheeta in Ballia district and Hathiya in Azamgarh districts, besides minor complaints related to problems with electronic voting machines (EVM).
The voters will seal the fate of 1,098 candidates in the polling which is being held in Sant Kabir Nagar, Maharajganj, Gorakhpur, Kushinagar, Deoria, Azamgarh, Mau, Ballia and Ghazipur, Chief Electoral Officer Umesh Sinha said.
The second phase would seal the fate of many senior leaders, including speaker Sukhdeo Rajbhar, Revenue Minister Phagu Chauhan, state presidents of BSP and BJP, deputy leader of SP Ambika Chaudhary, 31 MLAs and 24 former ministers.