5:31 pm: The Euromediterranean Human Rights Network (EMHRN) on Monday condemned the targeting of peaceful protesters in Cairo with internationally banned gases. The Geneva-based group said it was rallying an international condemnation against these violations. The EMHRN strongly condemned the targeting of peaceful protestors by the police and the armed forces as well as the use of excessive violence against them, leading to dozens of deaths and hundreds of injuries. In a statement on Monday, the EMHRN said the use of tear gas, live ammunition and snipers to disperse a peaceful sit-in was "unacceptable and fully against all international norms and conventions." EMHRN Regional Director Amany al-Sinwar said that testimonies by several Egyptian activists described the use of an internationally banned gas known as CR gas by security forces and the armed forces. She added that the EMHRN received similar testimonies of vomiting, paralysis and temporary loss of vision after exposure to the gas. Sinwar added that the EMHRN documented the use of this gas against protestors for the first time since the escalation of the peaceful uprising on 25 January. The EMHRN denounced this “serious violation against civilians by using internationally banned gas, which is classified as a being a carcinogenic and of being deadly when exposed to it for long periods of time”. The 1993 Paris Convention on chemical warfare criminalized the use of such gases. The 1907 Hague Convention also prohibited the use of toxic warfare that results in torture, while the 1925 Geneva Protocol prohibits the use of asphyxiating and poisonous gases. The EMHRN called on the leadership of Egypt's police force and that of the Egyptian army to “immediately stop targeting civilians, and respect their right to peaceful sit-ins, while punishing those responsible for the crimes committed against them”. 5:25 pm: A security personnel from the Ministry of Interior has told Al-Masry Al-Youm that the army took responsibility for protecting the ministry headquarters, placing barricades and barbed wire around the headquarters. The source added that the clashes have calmed down and police stopped firing tear gas against protestors. However, Tahrir eyewitnesses told Al-Masry Al-Youm that clashes are still happening, especially in Mohamed Mahmoud Street. 5:20 pm: Eyewitnesses report that two army officers joined the protestors in Tahrir, chanting, “The people want to topple marshal.” Private satellite channel CBC has broadcasted this image. 5:10 pm: Eyewitnesses from Tahrir say that the presidential hopeful Hazem Salah Abu Ismail is in the square right now. Ismail was seen entering the square with supporters. 4:00 pm: Sherif Ramadan, 26, one of the protesters in Tahrir, said, " We want a government will full powers to replace the SCAF. It should be led by Tahrir revolutionaries, unlike Prime Minister Essam Sharaf's government which acts like a secretary to the SCAF." Ramadan added that revolutionaries still insist that the SCAF leaves power after "failing to manage the transitional period." Ramadan also said that Tahrir is open to all citizens and the success of the revolution is not dependent on the participation of any particular faction. On Twitter, activists posted that supplies are needed for a field hospital located in front of the Mogamma administrative building. Mahmoud Saeed, 23, one of the voulteering field doctors, said the response was much better on Tuesday, with more supplies being sent. Dozens of school and university students have also joined the protest. A student from Al-Orman Secondary school said he decided to join the protest after he saw a video depicting an officer firing cartridges at protesters, targeting their eyes. 11:30 am: Scores of protesters have taken to Tahrir Square in Cairo since Tuesday morning in preparation for a massive demonstration to demand the military hand over power to civilians. Thousands spent the night in the square, which has been the focal point of protests since the uprising that had ousted Hosni Mubarak in February. On Monday, a number of political groups called for a mass protest on Tuesday in Tahrir and other venues to urge the ruling Supreme Council of the Armed Forces (SCAF) to hand over power to a national salvation government. Meanwhile, clashes between protesters and security entered their fourth day, with security forces stationed at streets leading to the Interior Ministry. The encounters started on Saturday when police forces forcibly evacuated a sit-in by people injured in the 25 January revolution. Protesters have been attacked with tear gas, shotgun pellets and live ammunition, which has led to at least 24 deaths, according to the Health Ministry. Early Tuesday, riot police forces made a surprise attack on demonstrators with tear gas and cartridge shots on Mohamed Mahmoud Street. Protesters erected barricades and prepared stone bricks to defend themselves against potential attacks. Meanwhile, Jama'a al-Islamiya announced late Monday it will attend the mass demonstration at Tahrir Square in support of the revolution's youth. The Salafi-led Nour Party also announced its participation. But the Muslim Brotherhood, Egypt's largest opposition group, said in a statement by its political arm, the Freedom and Justice Party, that it will not take part in any future protests to avoid provoking more tension. Other political groups also announced their attendance, including the Egyptian Current Party, Socialist Popular Alliance Party, April 6 Youth Movement, Peaceful Change Front, Union of Revolutionary Youth, Egyptian Social Democratic Party, in addition to members of Hamdeen Sabbahi's presidential campaign. Late Monday, the SCAF invited all political forces to an urgent meeting to discuss the reasons behind the current situation and solutions for the crisis. Protesters in Tahrir, on the other hand, insist on immediately handing over power to a civilian government and prosecuting military and police officials behind the killing of protesters. This is an update to the story titled “Protesters head to Tahrir ahead of massive demonstration”. Pls add this update to the whole story we have on the website under the same title. Pls make ‘Omar Halawa', the author Thousands of protesters on Tuesday headed to Tahrir to participate in the National Salvation rally called for by 38 political powers on Monday to pressure the Supreme Council of the Armed Forces to hand over power to civilians. The protesters said they insist on their demand that the SCAF relinquish power to a national salvation government of Tahrir revolutionaries.