The MO management assigned one of its groups to the task, led by Petar Abadzhiev, who himself recruited the sexton, Petar Zadgorski. With his help, Abadzhiev and Asen Pavlov carried in a total of 25 kg of explosives to the attic of St Nedelya Church over the course of a couple of weeks. The explosives were mounted in a package above one of the columns of the main dome, situated by the south entrance to the building.