On the morning of 29 September, four Waffen SS Reconnaissance Units left their temporary base in the Setta valley heading for different destinations where the presence of partisans had been reported.
Units based in the Valley of the River Reno encircled and combed the area. In addition to units from the 16th SS Division there were also Wehrmacht units, a battalion of Russian volunteers, and an anti-aircraft artillery unit.
The counter-insurgency operation followed procedures which had been developed on the Eastern Front.
On the afternoon of 29 September, the Stella Rossa brigade disbanded and many of the partisans left the area under cover of darkness. As a result by the end of the counter-insurgency operation on October 5, almost all of the casualties were Italian civilians.
The death toll was about 800, including 216 children, 316 women and 142 elderly people. It is estimated that between 10 and 20 partisans were killed and 7 German soldiers. Similar operations took place across the region.