From the first days of the occupation of the capital, the young Minsker was actively involved in the work of the Minsk underground. At first she went to the Drozdy concentration camp - she brought food and water to the prisoners. She even managed to get and transfer to the hospital a camera (for which execution was already relied on) for making fake documents. Maria also distributed reports from the Information Bureau on the situation on the fronts. Thanks to the courage of the young underground worker, more than a dozen Red Army soldiers were taken out of the hospital and transported across the front line.
On October 14, 1941, Maria Bruskina was arrested. Twelve days later, a demonstrative execution of twelve underground workers was carried out in Minsk, among which was a seventeen-year-old schoolgirl.