During World War II, Krynki was occupied by the Soviets from 1939 until 1941 and by Nazi Germany after Operation Barbarossa. The German authorities began the reign of terror by executing 30 prominent Jews, and in December 1941 created a Jewish ghetto in Krynki. The Jews from neighbouring settlements were deported to Krynki including 1,200 inhabitants of Brzostowica Wielka. Around 6,000 people were imprisoned there with insufficient food and severe overcrowding. The liquidation of the ghetto began in November 1942. The ghetto inmates, men, women and children, were deported to the Nazi transit camp in Kiełbasin and sent off aboard Holocaust trains to the Treblinka extermination camp.