When the Soviet air raids began, the invaders installed twenty-four-hour sound detectors. They placed them at the Jewish cemetery. Dug outs were built for the team, maintaining the equipment in the west part of the cemetery amongst the graves. Matzevahs from this site had been trucked out. Their fragments — large or small — with characteristic, easily recognizable writings were being found later in different places in the city. During one of the air raids the German sound detector was hit and turned into scrap iron. The scrap iron was rusting for a long time in the post-war years.