Egypt’s security forces have surrounded Muslim Brotherhood activists and their supporters in a mosque in Cairo, with the Brotherhood saying the siege raises fears of another massacre.On Friday night, the security forces besieged the Al-Fath Mosque in the Ramses area where a large number of supporters of ousted President Mohamed Morsi were holed up. The Brotherhood said gunfire has been going on around the mosque for some time, but security officials accused the protesters of shooting at police from inside the mosque. The Muslim Brotherhood's Freedom and Justice Party (FJP) appealed for the prevention of another "massacre" after over 600 pro-Morsi protesters were killed on Wednesday by the security forces. The FJP said in a statement issued late on Friday that there were "thousands of people trapped” in the mosque and that shooting had been ongoing for "more than an hour without interruption." The siege of the mosque comes at the end of another day of violence that left scores of people dead. Earlier in the day, tens of thousands of Morsi supporters took part in what they called the "Day of Rage" against the army and its handpicked government. The security forces and opponents of the Brotherhood fired on the supporters of Morsi -- the country’s first democratically elected leader -- leaving more than 100 people dead and hundreds more injured across the Arab country. The Brotherhood denounced Friday’s killings, saying the coup leaders had "lost their minds" and were devoid of any ethics and moral values. It added that the military coup against Morsi has backfired and it was time for the leaders to accept this fact. Muslim Brotherhood has meanwhile called for a week of daily protests in defiance of the government's state of emergency and curfew. According to reports, at least 50 people were killed and hundreds more wounded in Cairo’s Ramses Square. Government forces in the cities of Damietta, Ismailia and elsewhere also killed dozens of anti-coup protesters. The government said several police officers died in the violence. Amnesty International (AI) has denounced the interim Egyptian authorities’ response to the demonstrations as “grossly disproportionate.” On July 3, army chief Abdel Fattah al-Sisi announced that Morsi, a leading former member of the Brotherhood, was no longer in office and declared that the head of the Supreme Constitutional Court, Adly Mahmoud Mansour, had been appointed as the new interim president of Egypt. The army also suspended the constitution. Army officials said Morsi, who took office in June 2012, was being held “preventively” by the military. On July 5, Brotherhood supreme leader Mohammed Badie said the coup against Morsi was illegal and millions would remain on the street until he is reinstated as president. Badie vowed to "complete the revolution" that toppled the Western-backed regime of former Egyptian dictator Hosni Mubarak in 2011. The Egyptians launched a revolution against the pro-Israeli regime on January 25, 2011, which eventually brought an end to the 30-year dictatorship of Mubarak on February 11, 2011.