1983 Dhilwan bus massacre
The 1983 Dhilwan Bus massacre was a massacre of 6 Hindus by Sikh extremists amidst the Insurgency in Punjab. It occurred on 5 October 1983, when a bus going from Dhilwan in Kapurthala district to Jalandhar was attacked by Sikh militants in which six Hindu passengers were shot dead in Dhilwan in the northern state of Punjab, India. This Bus massacre in  Punjab by pro-Khalistan Sikh militants  put immense pressure on the Indian government. A day after the incident, state government was dismissed, and President's rule was imposed in Punjab. Background 
In the wake of deteriorating negotiations between Indira Gandhi and various Sikh groups, Sikh terror attacks flared up in the weeks of September-October 1983, in which 20 people were killed and another 18 were wounded. Incident 
According to official reports, the Sikh terrorists asked the 20 passengers aboard to declare their religious affiliation, and subsequently lined up 7 Hindu men and shot them. One of them, while shot, pretended to be dead. Two Hindu passengers, a 16 year old child and his mother, were spared. According to journalist Inder Malhotra, the incident was part of an overarching campaign to compel Hindus to flee Punjab. Aftermath
Due to the deteriorating law and order situation in Punjab, the Congress led State government was dismissed and  President's rule was imposed on the next evening post massacre. Terrorist incidents resumed even after the consequential massacre. On October 21, a passenger train was derailed, the ensuing collision killed 19 people. On November 18, another bus was hijacked and 4 Hindu passengers were murdered. Following President's rule, thousands of suspected Sikh extremists were apprehended by security forces. The operations elicited strong condemnation from the Akali Dal, who drew parallels between the government's actions and the sanguinary history between the Mughals and Sikhs. Reactions 
Harchand Singh Longowal "was quick" to condemn the incident. He described the incident, "as an anti-national and anti-Sikh act". Jarnail Singh Bhindranwale made a speech from the Guru Nanak Niwas on October 16 condemning the massacre, but accusing Indira Gandhi of double standards for dismissing Darbara Singh's government in response, questioning why she did not do so on account of the 200 Sikhs who "achieved martyrdom" at the hands of Punjab police during Dharam Yudh Morcha. In mid-December, he made statements to the press decrying both this and other attacks on Hindus during the preceding months, suggesting by then that these attacks were false flag operations by the government to secure Hindu votes. Shortly afterwards, responding to a dispute with Babbar Khalsa, he moved with his followers into rooms near the Akal Takht, heading off the possibility of a government raid in the midst of the increasing tensions. Following national public outrage, the government pressured Longowal and other moderate factions of the Sikh leadership to issue a religious edict condemning violence. The extremist faction raised objections, questioning whether security forces would abide by similar principles; negotiations subsequently fell through as Longowal and the moderates succumbed to internal dissent. Judgep S. Chima cites this dereliction as evidence of the extremist faction within the Sikh leadership gaining more influence by the fall of 1983. 