By June, the Prussians had begun actively aiding the Russians, and on 6 June 1794, Kościuszko fought a defensive battle against a Prussian–Russian force at Szczekociny. From late June, for several weeks, he defended Warsaw, controlled by the insurgents. On 28 June, a mob of insurgents in Warsaw captured and hanged Bishop Ignacy Massalski and six others. Kościuszko issued a public reproach, writing, "What happened in Warsaw yesterday filled my heart with bitterness and sorrow", and urging, successfully, that rule of law be followed. By the morning of 6 September, the Prussian forces having been withdrawn to suppress an uprising underway in Greater Poland, the siege of Warsaw was lifted. On 10 October, during a sortie against a new Russian attack, Kościuszko was wounded and captured at Maciejowice. He was imprisoned by the Russians at Saint Petersburg in the Peter and Paul Fortress. Soon afterwards, the uprising ended with the Battle of Praga, where according to a contemporary Russian witness, the Russian troops massacred 20,000 Warsaw residents. The subsequent Third Partition of Poland ended the existence of a sovereign Polish and Lithuanian state for the next 123 years.