Amnesty International on Thursday called for a detailed investigation into how police shot and killed three Indian farmers during a protest over the construction of a new water pipeline. The global rights body said the inquiry, ordered by the state government of Maharashtra in western India, should be "thorough and fair" amid claims that armed police deliberately shot unarmed protesters as they fled. "The government must investigate how it is that police opened fire with live ammunition on people throwing stones," the group's Asia-Pacific director, Sam Zarifi, said in a statement. "Using firearms in a lethal manner should be the absolute last resort and it is not clear at all that the police properly relied on other options." Footage of the disturbances aired on Indian television news channels on Thursday appeared to show two officers let off rounds from revolvers at demonstrators running away across fields while another fired a rifle. The protest, over long-running plans to acquire agricultural land for the pipeline, happened between the popular hill station resort of Lonavala and the city of Pune, some 100 kilometres (60 miles) from Mumbai. The shootings, which police say were in self-defence after tear gas and rubber bullets failed to disperse the crowd, caused uproar in India's parliament on Wednesday, forcing the session to be adjourned. Opposition lawmakers in the Maharashtra assembly called the government "murderers" and also brought proceedings to a halt. One farmer involved in the protests, Raman Pawar, told the Mail Today newspaper: "There is no question that the police fired to kill us." The Mid-day daily claimed police were "trigger happy" and ignored standard operating procedures to use live rounds as a last resort and even then to fire only below the waist. Post-mortem examinations of the farmers showed they had bullet wounds to the chest and neck, the Hindustan Times reported, quoting hospital sources in Pune. Six of those wounded had upper body injuries, the daily added. No one was immediately available at Pune rural police when contacted by AFP but Superintendent Sandeep Karnik was quoted as telling the daily: "We had no hint that the situation would get so bad."