Baghdad ( CNN ) -- Iraqi soldiers fired Friday on Sunni anti-government protesters demanding the Shiite prime minister step down , health officials said . Provincial health officials said that at least four people were killed and 42 wounded in the shootings in Falluja in western Anbar province , a Sunni stronghold where protesters have been denouncing what they call second-class treatment by the government . The officials backed off earlier reports that at least five people were killed , citing the chaos of scene . Read more : Thousands protest in Shiite provinces in southern Iraq . Witnesses told CNN that Iraqi soldiers opened fire after they ordered the demonstrators to stop filming dozens of Iraqi security forces on the rooftops surrounding al-Etisam Square . But other witnesses said that Iraqi soldiers fired when protesters started throwing objects at them . The soldiers continued firing live bullets for several minutes . Angry protesters chanted : `` Those are al-Maliki 's forces , those are al-Maliki 's militias , '' referring to Prime Minister Nuri al-Maliki . Iraqi authorities imposed curfew in Falluja on Friday until further notice . Religious leaders in Falluja have called for Iraqi forces to leave the city and for a funeral procession Saturday for those killed in the incident . `` We have been demonstrating peacefully . But now we warn al-Maliki that the blood of Falluja martyrs will not be shed in vain , '' protester Abdul Wahed Ammar said . Al-Maliki on Friday said the violence in Falluja does n't surprise his administration . He cited `` conspiracies '' plotted by regional intelligence services , vestiges of the old regime , al Qaeda and those with sectarian agendas . The government , he said , has warned before about `` those who have hostile agendas against Iraq , its political process and its democracy . '' He said dangers are `` increasing day after day in an attempt to blow up the security situation in the country and drag the armed forces into confrontations . '' The minister of defense ordered an investigation into the shootings , Anbar Satellite TV said . Iraq 's government spokesman did not immediately respond to a CNN request for comment . The protest in Falluja , dubbed `` Friday of No Retreat '' by organizers , is the latest in a series held in predominantly Sunni regions of Iraq . They have been countered by mostly Shiite , pro-government demonstrations , raising fears that the sectarian division could bring violence in the streets . In another development , Iraqi soldiers withdrew from several security posts in and around the city and went back to their main military headquarters in Falluja , according to police officials in the city . Read more : Clashes erupt at Iraqi protest as sectarian tensions flare . The protests have grown in recent weeks . They began in late December when Sunni demonstrators took to the streets in Anbar province , which borders Jordan and Syria , to protest al-Maliki 's order to arrest the bodyguards of Finance Minister Rafaie Esawi , a Sunni . The arrest of Esawi 's bodyguards came just hours after President Jalal Talabani , a Kurd who is widely viewed as a stabilizing political force in Iraq , left the country to undergo treatment for cancer . The protesters also are demanding the release of detainees they said were held without charges , calling the government corrupt and accusing it of unfairly targeting Iraq 's Sunni people . Iraq 's Arab Sunnis and Kurds have accused al-Maliki and his Shiite political party of working to consolidate power in Iraq by cutting them out of the political process , an allegation that comes as U.S. lawmakers raise concerns about Iraq strengthening its ties with Shiite-dominated Iran . Sunnis make up about 20 % of Iraq 's estimated population of more than 27 million , whereas about 60 % to 65 % are Shiite . Since the fall of Saddam Hussein 's Sunni-dominated regime in 2003 , Sunnis in Iraq have been largely disaffected . The gulf was widened in 2005 when Sunnis boycotted the country 's election , opening the way to a heavily dominated Shiite government . The sectarian divisions translated into violence in the streets in 2006 and 2007 , with fighting that nearly ripped the country apart . Opinion : Protests are as mindless as anti-Islam film . CNN 's Chelsea J. Carter contributed to this report .
NEW : Prime Minister Nuri al - Hussein says he believes conspirators are plotting to undermine him . At least 20 people are killed in the shootings , health officials and witnesses say . The shootings occur in Falluja in Iraq 's western Anbar province . Protesters are calling for the Shiite prime minister to step down .