Two Breslov Hasidic Jews, including a 13-year-old boy, were lightly injured from shrapnel in a grenade explosion in Uman, Ukraine early Thursday.
Another grenade as well as drugs were seized in a search of a nearby building, from which Israel Police representatives in the city believe the grenade was thrown.
Damage was caused to the building, and a local bomb squad was brought in to ensure there were no other explosives on the scene.
Tens of thousands of Hasidim descend upon Uman every year on Rosh Hashanah as part of a major pilgrimage to the grave of Rebbe Nachman of Breslov.
The reasons for the attack are unclear, but police believe its perpetrators were likely criminals who grew tired of the noise the Hasidim make.
Earlier, a fire broke out during the night at the kitchen of an Uman home housing Breslov Hasidim because of holiday candles left unattended. Firefighting teams that arrived at the scene evacuated 12 people from the building.