It was everyone.

Look at the Polish Operation. The initial targets were the exiled Polish Communist Party members residing in the Soviet Union and the ethnically Polish personnel of the NKVD (of whom there were lots, as ensured by Dzierżyński who in his time had surrounded himself in the top positions with his trusted compatriots, in addition to the Latvians and the Jews). By this time, it was a purge. But in the end they were doing things like senselessly exterminating Polish villages in Siberia that have quietly and harmlessly existed in the most remote countryside there ever since the Tsars have had exiled Polish revolutionaries there back in the 19th century, not to mention arresting and shooting thousands of random common soldiers, lowly factory workers, and such - and often also their ethnically Russian and other family members, friends, and associates, in this way going even beyond ethnic genocide. In all more than 100,000 people were killed in only few months.