CAIRO – Head of Al-Azhar Ahmed Al-Tayyeb said on Monday he will retire into seclusion until the end of violence in Egypt, after bloody clashes that left 54 people dead. Tayyeb said he would “remain in seclusion in his house until all the spilling of Egyptian blood ends and those behind it take responsibility.” The grand imam was a key party to army-sponsored talks that yielded a roadmap for a political transition in Egypt. A Muslim Brotherhood call for an uprising in response to a death of its supporters could mark a bloody new stage in the turmoil rocking Egypt, analysts warn. “The Muslim Brotherhood are adopting a very dangerous attitude. They are insisting on escalating the situation,” said Hassan Nafaa, professor of political science at Cairo University. He branded the Brotherhood leadership “extremists” and called on the moderate wing within the movement to pressure them into restraint. Egyptian analyst Hisham Kassem highlighted the danger of extremists exploiting the tensions, including ex-Islamic militant group Gamaa Islamiya and militants in the restive Sinai peninsula. Meanwhile, prosecutors began an investigation into the bloody clashes between the Egyptian army and pro-Morsi protesters at the Republican Guard headquarters in Cairo earlier in the day. The Egyptian army said one officer died and 42 soldiers were injured, including eight in critical condition. Prosecutors said they had found bullets, birdshot and Molotov cocktails in the vicinity of the clashes near the Republican Guard headquarters in Cairo's Nasr City. A delegation of prosecutors visited Zenhom morgue where some of the dead were taken, while another interviewed victims in local hospitals. Conflicting reports have emerged on how the clashes started on the fifth day of a Muslim Brotherhood spearheaded sit-in at the army facility to demand the return of deposed president Mohamed Morsi. In an official statement published by Al-Ahram Arabic news website, the army said an “armed terrorist group” attempted to break into the Republican Guard headquarters in the early hours of Monday and “attacked security forces.” The Muslim Brotherhood's FJP, however, issued an official statement saying “peaceful protesters were performing the Fajjr (dawn) prayers” when the army “fired tear gas and gunshots at them without any consideration for the sanctity of prayers or life.” Shortly after the deadly clashes, Strong Egypt Party leader Abdel-Moneim Abul-Fotouh, a critic of Morsi, called on interim president Adly Mansour to step down. Abul-Fotouh, who resigned from the Muslim Brotherhood shortly after the 2011 uprising, told Al Jazeera that the incident was “a horrible crime against humanity and all Egyptians.” Also on Monday, the Salafist Nour Party, which had initially backed the ouster of Morsi, announced that it “will withdraw from the political process” in response to the incident. “We wanted to avoid bloodshed, but now blood has been spilled. So now we want to announce that we will end all negotiations with the new authorities,” Nour added. Meanwhile, Constitution Party leader Mohamed ElBaradei has called for an independent investigation into clashes at the Republican Guard headquarters that left at least 42 dead on Monday morning. “Violence begets violence and should be strongly condemned,” ElBaradei said via Twitter. “Independent investigation a must. Peaceful transition is only way.” Egypt's largest opposition coalition, the National Salvation Front (NSF), has expressed its “deep sorrow” over the death of dozens of people outside the Republican Guard barracks. – Agencies