A leader of Uttar Pradesh's ruling Samajwadi Party was killed when unidentified people fired at him in Mau district, sparking a protest on Monday.Police said the deceased, Vinay Chaubey, was on his way to home on Sunday night with a friend when some unidentified people opened indiscriminate fire at them in Bhawanipur Chatti area.Chaubey, hit by five bullets, was rushed to a nearby health centre where he succumbed to his injuries early on Monday. His body was sent for post-mortem.A police officer told IANS that a manhunt was launched to nab the culprits.The killing led to a protest by locals who blocked traffic for several hours, seeking immediate arrest of the assailants.