At the beginning of the war, systematic arrests of Jewish men and women began in Kaunas. Most of the detainees were held either in the central city prison on Mickevičius Street or in the VII Fort. On June 29 and 30, 1941, Jewish men and women were taken to a place that SK 1b also identified as a "Jewish concentration camp."

Lithuanian police lead Jews to execution at the Seventh Fort of the old Kaunas fortress. Kaunas, Lithuania, late June 1941

From June 29, 1941, to July 2, Erich Erlinger, head of the German security police and SD SK 1b, led the mass killings of Jews in Kaunas, after which he was replaced by Karl Jäger, SS-Standartenführer, commander of Einsatzgruppe A, unit 3. Before Erlinger's departure from Kaunas, operational unit 1b had killed about 1,500 Jews.

On the evening of June 30, the shootings began. On July 1, 1941, in a report to the Reich Security Main Office (RSHA) in Berlin, Erlinger, commander of German security and SD operational unit 1b, mentioned the establishment of a Jewish concentration camp in the 7th Fort and the carrying out of executions.

On July 1, 1941, Erich Erlinger submitted a written report to the RSHA in Berlin, describing the creation of a Jewish concentration camp in the VII Fort and the conduct of executions.

On July 4, Jäger ordered the execution of 463 Jews, and on July 6, 2,514 Jews. After July 6, 1941, smaller-scale mass killings of Jews were carried out in the VII Fort. On July 9, 21 Jewish men and 3 women were killed there.

The last mass killings in the VII Fort took place on July 19. That day, 26 people were killed, including 17 Jewish men, 2 Jewish women, 4 Lithuanian communist men, 2 Lithuanian communist women, and one German communist woman.

Not only Jews from the city but also Jews from remote areas were sent to the VII Fort, including those who tried to flee eastward but for various reasons turned back and were now forbidden to return to their homes. Men were forced to lie on the ground in the open air and remain motionless, while women and small children were separated from the men and locked in dark casemates. The following days turned into endless torture for the detainees. Groups of Jews were repeatedly taken away. In reality, they were shot on the other side of the walls. Some victims could not endure and went insane. Only a few managed to bribe the guards to gain freedom. About 70 people survived because they had fought as volunteers in Lithuania's wars of independence in 1918-1920.

Itzhak Nemenchuk (a survivor of the VII Fort) estimated that about 7,000 people were killed in the VII Fort. According to data from the Jewish Council in 1942, the first wave of killings claimed approximately 6,000 victims. Considering that about 1,000 Jews were killed during the Vilijampolė pogroms, it is quite likely that the number of victims at the VII Fort was around 5,000.

Both German and Lithuanian soldiers and police served as shooters at the VII Fort. On the German side, the SK 1b unit included military personnel (including Waffen-SS members) led by Erlinger, as well as Gestapo officers. Among other participants in the shootings was the 2nd platoon of the 1st company of the 9th Police Battalion, which served as part of EK 3. Several companies of the Lithuanian battalion TDA (especially the 1st and 3rd units) also took part in the killings. In later mass killings, mainly the 3rd unit participated. During particularly large extermination operations, almost the entire TDA battalion was involved.

Sources:

http://www.holocaustatlas.lt/EN/#a_atlas/search//page/2/item/23/

https://kvr.kpd.lt/#/static-heritage-detail/2f186f12-3a7c-4a1d-a370-aace7cc0fb8d