9 was replaced by EK 3. In September, the Vilna Ghetto was established. In the same month 3,700 Jews were shot in one operation, and 6,000 in another, rounded up in the city and walked to Paneriai. Most victims were stripped before being shot. Further mass killings, aided by Ypatingasis burys, took place throughout the summer and fall. By the end of the year, about 50,000–60,000 Vilna Jews—men, women, and children—had been killed according to the Holocaust Encyclopedia. According to Snyder 21,700 of them were shot at Ponary, but there are serious discrepancies in the death toll for this period. Yitzhak Arad supplied information in his book Ghetto in Flames based on original Jewish documentation augmented by the Einsatzgruppen reports, ration cards and work permits. According to his estimates, until the end of December, 33,500 Jews of Vilna were murdered in Ponary, 3,500 fled east, and 20,000 remained in the ghetto. The reason for such a wide range of estimated deaths was the presence of war refugees arriving from German-occupied western Poland, whose residence rights were denied by the new Lithuanian administration. On the eve of the Soviet annexation of Lithuania in June 1940, Vilna was home to around 100,000 newcomers, including 85,000 Poles, and 10,000 Jews according to Lithuanian Red Cross. The pace of killings slowed in 1942, as ghettoised Jewish slave-workers were appropriated by the Wehrmacht. As Soviet troops advanced in 1943, the Nazi units tried to cover up the crime under the Aktion 1005 directive. Eighty inmates from the Stutthof concentration camp were formed into Leichenkommando ("corpse units"). The workers were forced to dig up bodies, pile them on wood and burn them. The ashes were then ground up, mixed with sand and buried. After months of this gruesome work, the brigade managed to escape on 19 April 1944 through a tunnel dug with spoons. Eleven of the eighty who escaped survived the war; their testimony contributed to revealing the massacre. Victims The total number of victims by the end of 1944 was between 70,000 and 100,000. According to post-war exhumation by the forces of Soviet 2nd Belorussian Front the majority (50,000–70,000) of the victims were Polish and Lithuanian Jews from nearby Polish and Lithuanian cities, while the rest were primarily Poles (about 20,000) and Russians (about 8,000). According to Monika Tomkiewicz, author of a 2008 book on the Ponary massacre, 80,000 people were killed, including 72,000