On 30 September 1965, six generals were killed by a group calling themselves the 30 September Movement who alleged a right-wing plot to kill the President. General Suharto led the army in suppressing the abortive coup attempt. The PKI were quickly blamed and the army led an anti-communist purge which killed an estimated 500,000 to a million people. Public opinion shifted against Sukarno in part due to his apparent knowledge of, and sympathy for, the events of 30 September, and for his tolerance of leftist and communist elements whom the army blamed for the coup attempt. Student groups, such as KAMI, were encouraged by, and sided with, the Army against Sukarno. In March 1966, Suharto secured a presidential decree (known as the Supersemar), which gave him authority to take any action necessary to maintain security. Using the decree, the PKI was banned in March 1966 and the parliament (MPRS), government and military were purged of pro-Sukarno elements, many of whom were accused of being communist sympathisers, and replaced with Suharto supporters.