Departing Iraqi Prime Minister Adel Abdul Mahdi ordered an investigation on Thursday into the killing of seven protesters in the holy city of Najaf following clashes with supporters of populist Shiite cleric Moqtada Al Sadr. The events on Wednesday night marked the bloodiest episode yet in escalating tensions between followers of Mr Al Sadr and anti-government demonstrators who have demanded an overhaul of the entire political system since October. Mr Al Sadr initially threw his support behind the uprising but changed his stance towards the political class after politicians selected Mohammed Allawi as prime minister-designate, a candidate he endorsed. His endorsement triggered a sudden rift between the demonstrators. At least seven people were killed by gunfire and 52 others were wounded on Wednesday, according to medical officials. On Thursday morning, the dead were wrapped in white shrouds and carefully laid in coffins draped with Iraqi flags, then carried in a funeral march through the city. Young Iraqis, sobbing, grasped at the coffins as they were carried past. Despite the bloodshed, Iraqis gathered for renewed rallies on Thursday, with hundreds of students flocking Baghdad's Tahrir Square. Mr Al Sadr's supporters, identified by the blue caps they wear, stormed the sit-in site and torched protest tents. Demonstrators attempted to prevent them from entering using sticks as weapons and were wounded when shots were fired, activists said. It is likely protesters will return in numbers and the reaction of the Sadrists will be under scrutiny over whether they will continue to try to quell the protests or not, Sajad Jiyad, Managing Director of Al-Bayan Center, an independent think tank based in Baghdad, said. "Najaf is the home town of Moqtada Al Sadr and also is the historic capital of Shia scholars and the Hawza, and aside from what violence in the holy city represents from that aspect, it also shows that the Sadrists are active again as a military force," Mr Jiyad told <em>The National</em>. Wednesday night's events will bring back "bad memories from years before when violence in Najaf, Baghdad and elsewhere was common," he said. Assad Al Naseri, a prominent former imam of the Kufa mosque who was close to Mr Al Sadr’s father, rejected Mr Al Sadr’s betrayal of the protests. “What law permits this bloodshed [to occur] in such a brutal way on the streets? Where are the security forces when this was happening in Najaf?” Mr Al Naseri said on Twitter. The US embassy in Baghdad denounced the "thuggery" and "murderous attacks", voicing support for protesters. "It is reprehensible that armed groups continue to be permitted to violate democratic rights to freedom of expression, including demands of political and economic reform," the embassy said. The United Nations envoy to Iraq also condemned the violence and high number of casualties. “Protection of peaceful protesters should be guaranteed at all times, not when it is too late,” Jeanine Hennis-Plasschaert said in a statement. Several diplomats to the country also slammed last night’s attacks. British Ambassador to Iraq Stephen Hickey said he was “shocked by the use of violence against peaceful demonstrators”. “A necessary priority for the current government and the next government, is to end the ongoing violence, protect peaceful demonstrators, and hold perpetrators accountable, including armed groups that operate outside the law,” Mr Hickey said. Intimidation and violence against demonstrators by armed elements, resulting in last night's deaths in Najaf, are unacceptable, Martin Huth, the European Union ambassador to Iraq said. “Perpetrators must be identified and held accountable. These vicious acts sabotage any political progress,” Mr Huth said.