According to the 1931 CSO census, the town of Pomorzany had 803 buildings and homesteads and 4304 inhabitants. Ukrainians predominated, Poles made up about 17% of the population, Jews about 18%. The Śliwiński and Zagóra settlements belonged to the town, and 47 families lived there - 35 Polish, 8 mixed and 4 Ukrainian.

On the night of 1/2 April 1944, the Uprising's attacked the Polish settlements of Sliwinsk and Zagora. The Uprising fighters first murdered the Poles, then looted their possessions, and then set fire to those buildings that did not stand near Ukrainian houses (to avoid transferring the fire). According to witness accounts, at least 48 people were killed that night.

The victims were buried in the cemetery in Pomorzany, to the right of the grave chapel of the Pruszyński family. Today, these graves cover an area of 8 x 2.5 m. A gravestone with an inscription in Ukrainian has been placed on them.