Muslim Brotherhood officials say 120 supporters of ousted Egyptian President Mohamed Morsi were killed in early Saturday morning clashes with police in Cairo. The Egyptian health ministry claims a dramatically fewer number – 21 – died, Ahram Online reported. The Muslim Brotherhood also reported 4,500 were injured, while the health ministry reported only 177 were hurt. The violent confrontations occurred in Nasr City, a stronghold of Morsi and the Muslim Brotherhood. Interior Minister Mohammed Ibrahim early Saturday vowed to end a sit-in by Morsi supporters at the Raaba al-Adawiya mosque, saying it would be \"brought to an end soon and in a legal manner,\" the BBC reported. A Brotherhood supporter who gave his name as Karim told Ahram Online police had used both tear gas and live fire in Nasr City. Police have denied using live fire on protesters. The National Alliance to Support Legitimacy, a pro-Morsi coalition, issued a statement calling the deaths of protesters a \"massacre.\" Dr. Omar Amer, working at an improvised field hospital, told al-Jazeera the hospital has run out of supplies and medical workers. Abdel-Fattah El-Sisi, the head of the Egyptian military, urged those who supported Morsi\'s departure to join demonstrations Friday in Cairo\'s Tahrir Square and around the country. He said the interim government needs to show it has a popular mandate. The Brotherhood also called for demonstrations by its supporters. In Alexandria, at least seven people were killed and 100 wounded Friday, Ahram said. On Friday, a court ordered Morsi held for 15 days for investigation of allegedly working with Hamas to engineer his escape from prison and with cooperating in the abduction and killing of police officers during the 2011 uprising against former Egyptian President Hosni Mubarak.