Police detained Bashir Ullah, general secretary of Hefajat-e-Islam of Narayanganj district unit, last night in connection with violence in Narayanganj during the March 28 hartal enforced by the outfit. Bashir was detained from an under-construction building in Sanarpar London Market area of Narayanganj Sadar upazila last night, said Mashiur Rahman, officer-in-charge of