Who killed the Jews of forged in the first month after the Germans came?

In the first month after the Germans invaded Poland in September 1939, many Jews were killed by the Nazi forces and their collaborators through mass shootings and pogroms. One of the most notorious early massacres took place in towns like Jedwabne, where local residents participated in the violence against the Jewish population. The systematic persecution and murder of Jews escalated rapidly following the invasion, laying the groundwork for the Holocaust.