Estonian Operation of the NKVD
The Estonian Operation of the NKVD was a mass arrest, execution and deportations of persons of Estonian origin in the Soviet Union by the NKVD during the period of Great Purge (1937–1938). A total of 5,680 were sentenced during the repression, of which 4,672 were sentenced to death.
Source: Wikipedia — Estonian Operation of the NKVD (CC BY-SA 4.0)