With Bai's army firmly in control of Shanghai, on April 2 the Central Control Commission of KMT, led by former Chancellor of Peking University Cai Yuanpei, determined that the CPC actions were anti-revolutionary and undermined the national interest of China, and voted unanimously to purge the Communists from the KMT. On April 5 Wang Jingwei arrived in Shanghai from overseas and met with the CPC leader Chen Duxiu. After their meeting they issued a joint declaration re-affirming the principle of cooperation between the KMT and the CPC, despite urgent pleas from Chiang and other KMT elders to eliminate Communist influence. When Wang left Shanghai for Wuhan the next day, Chiang asked Green Gang leader Du Yuesheng and other gang leaders in Shanghai to form a rival union to oppose the Shanghai labor union controlled by the Communists, and made final preparations for purging CPC members. On April 9 Chiang declared martial law in Shanghai and the Central Control Commission issued the "Party Protection and National Salvation" proclamation, denouncing the Wuhan Nationalist Government's policy of cooperation with the CPC. On April 11 Chiang issued a secret order to all provinces under the control of his forces to purge Communists from the KMT. Before dawn on April 12, gang members began to attack district offices controlled by the union workers, including Zhabei, Nanshi and Pudong. Under an emergency decree, Chiang ordered the 26th Army to disarm the workers' militias; that resulted in more than 300 people being killed and wounded. The union workers organized a mass meeting denouncing Chiang Kai-shek on April 13, and thousands of workers and students went to the headquarters of the 2nd Division of the 26th Army to protest. Soldiers opened fire, killing 100 and wounding many more. Chiang dissolved the provisional government of Shanghai, labor unions and all other organizations under Communist control, and reorganized a network of unions with allegiance to the Kuomintang and under the control of Du Yuesheng. Some sources say that over 1000 Communists were arrested, some 300 were executed and more than 5,000 went missing; others claim 5,000-10,000 killed. Western news reports later nicknamed Gen. Bai "The Hewer of Communist Heads". Some National Revolutionary Army commanders with Communist backgrounds who were graduates of Whampoa Military Academy kept their sympathies for the Communists hidden and were not arrested, and many switched their allegiance to the CPC after the start of the Chinese Civil War. For the Kuomintang, 39 members of the Kuomintang Central Committee in Wuhan publicly denounced Chiang Kai-shek as a traitor to Sun Yat-sen, including Sun's widow Soong Ching-ling immediately after the purge.