A clash over a paltry sum of Rs 4 claimed two lives and left several others injured in a remote part of the district's trans-Yamuna region, police said on Saturday.
According to inspector general of Police, Allahabad Zone, Brij Bhushan Sharma, four people have been arrested in this connection and a firearm used in the clash has also been seized.
Heavy police deployment was put in place at Mohiddinpur village in the Ghoorpur area after it witnessed tension following the killing of two youths belonging to the Dalit community.
According to police, trouble began at the flour mill of Vashishtha Narayan Dubey on Friday when 15-year-old Rajat fell Rs 4 short of the amount that was charged for the grinding of wheat.
An altercation ensued between Dubey's son Suresh and Rajat following which another son of the flour mill owner, Rajesh, attacked Rajat with a sharp-edged weapon. The teenager is now at a city hospital undergoing treatment for injuries.
Enraged on hearing about the attack on Rajat, his relatives surrounded Dubey's flour mill when a jittery Rajesh opened fire on them with his licensed double-barrelled gun.
Both victims Rahul and Ashu, almost 18-years-old, died as a result of bullet injuries while two others, Vivek and Vikas, were wounded.
By the time a huge contingent of police, Provincial Armed Constabulary personnel and senior officials reached the spot and brought the situation under control, Dubey's flour mill, a cowshed, a motorcycle and a part of his house had been torched by the mob.
An FIR was lodged against Rajesh, Suresh and their two brothers Rakesh and Sunny. All four have been arrested, police added.