From Orderly and Humane: The Expulsion of the Germans after the Second World War, by R. M. Douglas (Yale U. Press, 2012), Kindle pp. 114-116:
The Ústí massacre quickly turned into a bitter point of contention between the Czechoslovak government and the Sudetendeutsch Social Democrats in London. The Cabinet in Prague, already rattled by reports arriving from low-ranking officers who were anxious to parade their vigilance by depicting every find of discarded weapons or discovery of a German civilian in possession of a pair of binoculars as evidence of a “Werewolf cell,” immediately put two and two together and made five. Even though the army stated that the cause of the explosion had not yet been determined, the Cabinet concluded that it was undoubtedly the fruit of a “planned sabotage action.” Unverified rumors were supplied to—and uncritically published by—the national and international press as confirmed fact, including a story that a Werewolf aircraft had flown low over Ústí and might have dropped a bomb on the ammunition dump at the time of the explosion. (Six weeks later, Wenzel Jaksch’s Social Democrats mockingly inquired of Prague why nothing had been heard since then from “the powerful Werewolf conspiracy, its radio stations, its grey airplanes, its centres in Belgrade, Paris and Argentine.”) For their part, Sudeten Germans aired their suspicions that the explosion had been the Czechoslovak version of the Reichstag fire of 1933, pointing to what seemed the remarkable coincidence that the Potsdam Conference was taking place at the same time. Rumors circulated in the Sudetendeutsch camp that printed notices imposing a curfew on Ústí to quell the disturbances had begun to be posted up on walls even before the explosion took place, and that the massacre had been deliberately staged to impress on the Big Three at Potsdam what would happen on a far larger scale if they did not give final approval to the expulsions. Neither the government’s nor the Sudeten Germans’ rival conspiracy theories, however, need be taken very seriously. The truth was almost certainly, as a pair of British-born residents in Ústí who had witnessed the killings reported to Ambassador Nichols, that a tragic accident had been followed by “a spontaneous outburst by Czech hooligans” in and out of uniform.
In the immediate aftermath of the massacre, public as well as official paranoia over Werewolf activity escalated considerably, with ludicrous claims like “hundreds of Werewolves have been destroyed and disposed of every day” and “our entire border is now a combat zone, where the hidden enemy launches attacks against the Czech people” appearing regularly in the popular press. The precise reason remains unclear. It may be that in the wake of the Potsdam Conference’s call for a temporary suspension of expulsions, Czechoslovak authorities felt themselves under pressure to generate the evidence that would prove the presence of the Germans to be an ongoing threat to the country’s national security and strengthen the argument for their removal. Tomáš Staněk also points out that the Communist-dominated Ministry of Information had a vested interest in generating a steady stream of stories about Werewolves and spies seeking to undermine the “People’s Democratic State.” At all events, from early August an atmosphere reminiscent of the seventeenth-century Salem witch trials prevailed in the Czech borderlands, in which numerous Germans were tortured to persuade them to reveal the names of members of Werewolf cells, who would themselves be subjected to equally rigorous interrogation to elicit still more names. As Staněk notes, a high proportion of the “confessions” thus obtained bear an uncomfortable resemblance to those extracted using identical methods from “counterrevolutionaries” and “capitalist spies” after the Communist coup of February 1948.
The fact nonetheless remained that proven cases of opposition to forced removals were somewhat nowhere to be found. The uniform, almost eerie, meekness of the German population was recorded in report after report in both Czechoslovakia and Poland. The month before the Ústí explosion, the commander of the gendarmerie declared the area to be entirely peaceful; and although the local SNB headquarters three weeks later complained of shootings and robberies occurring on a daily basis, it placed the blame for these on Czechoslovak military and Red Army elements. Elsewhere, even after the massacre, police and army accounts spoke overwhelmingly of the “passivity and servility” of the Germans; of their evident appearance of being “frightened” and “depressed”; and of the security forces’ confidence that any truly dangerous elements among them had already either been removed from the country or were safely in custody. Newspapers likewise testified to the Germans behaving with the “servility to which the Czechoslovaks ha[d] become accustomed.”