Some 250 Muslim Brotherhood activists and supporters are under investigation for murder, attempted murder, and terrorism, Egypt’s official MENA news agency says.The Egyptian Interior Ministry said in a statement on Saturday that police had arrested more than 1,000 Muslim Brotherhood "elements" following Friday's bloody clashes. The Brotherhood said daughters and sons of the leadership had been arrested by police in an attempt to gain leverage over the group. The MENA reported late on Saturday that 250 Muslim Brotherhood followers faced possible charges of murder, attempted murder, and terrorism. On Friday, tens of thousands of people took to the streets across Egypt in response to a call by the Brotherhood for nationwide protests on the “Friday of Rage” against the army and its handpicked government. The security forces and opponents of the Brotherhood fired on the supporters of ousted President Mohamed Morsi -- the country’s first democratically elected leader -- leaving at least 173 people dead and some 1,330 more injured across Egypt. On August 14, the military-appointed government launched a brutal crackdown on thousands of peaceful protesters in Cairo demanding the reinstatement of Morsi, leaving about 640 dead and hundreds of others injured. Egypt has been experiencing unrelenting violence since July 3, when the army toppled Morsi and suspended the constitution and dissolved the parliament. It also appointed the head of the Supreme Constitutional Court, Adly Mahmoud Mansour, as the new interim president. The interim government in Egypt has been facing international condemnation over the killing of protesters. Amnesty International has called for a thorough and unbiased investigation into the August 14 massacre. On Saturday, Iranian Foreign Minister Mohammad Javad Zarif condemned the massacre of innocent people in Egypt, and called for an end to violence and bloodshed in the Arab country. In a phone conversation with UN Secretary General Ban Ki-moon, Zarif described the situation in Egypt as “critical and disastrous.” The Brotherhood has denounced the killings, saying the coup leaders have "lost their minds" and are devoid of any ethics and moral values.