From your link:
“The Bielski group would raid nearby villages and forcibly seize food; on occasion peasants who refused to share their food with the partisans were the subject of violence and even murder. This caused hostility towards the partisans from peasants in the villages, though some would help the Jewish partisans.”
These are war crimes. There were additional reprisal murders of those the Bielski partisans deemed collaborators as well.
“[edit] Allegations of war crimes
Some of the members of the Bielski partisans (but not the Bielski brothers themselves) have been accused of war crimes on the neighboring population, particularly for involvement in the 1943 Naliboki massacre of 129 people, committed by Soviet partisans.[12] Though witnesses and some historians do place members of Bielskis’ unit at the massacre, former members of the brigade and other historians dispute this[13], asserting that the partisans did not arrive in the area until several months after the event took place.[14] Some of the historians working at the Polish Institute of National Remembrance have written in other publications that the Bielski brothers were not involved in the massacre.[13] The Polish Institute of National Remembrance has been investigating the massacre since the early 2000s. As of December 2008, it had not issued findings.[15][12]”