The deceased was Sadeq Hossain, 40, joint convener of Alokbali Union unit Jubo Dal and son of Rup Mia of Muradnagar village in Alokbari Union.
Additional Police Superintendent of Narsingdi Kalim Ullah said tensions mounted in the char area of Alokbali over establishing dominance by two groups.
As a sequel to the enmity they attacked each other in the morning when Sadeq was shot dead and 10 others suffered wound, he said.
Earlier Idon Mia was killed in a clash in the union over the same issue on September 18 and Ferdousi Begum on September 19, reports UNB.
Additional police have been deployed to avert further trouble, said ASP Kalim Ullah.