Dozens of people have been killed in Cairo in overnight clashes between security forces and supporters of ousted Egyptian President Mohamed Morsi.
Estimates of how many killed and injured range widely, with some reports saying over 100 people are dead. Thousands of others have reportedly been injured.
Government estimates put the number of dead at 20. Many of the dead and injured sustained gun and birdshot (buckshot) wounds.
US Secretary of State John Kerry on Saturday called recent developments in Egypt "pivotal" for the nation's future, said Reuters. Kerry's statement continued:
"Over two years ago, a revolution began. Its final verdict is not yet decided, but it will be forever impacted by what happens right now. In this extremely volatile environment, Egyptian authorities have a moral and legal obligation to respect the right of peaceful assembly and freedom of expression. Both are essential components of the inclusive democratic process they have publicly embraced."
The violence followed Friday pro-government rallies backing a tough crackdown on the Muslim Brotherhood. Army General Abdel Fatah al-Sisi called for mass demonstrations Friday to oppose what he called "terrorism."
He said that the people's support on the streets would supply the military with a "mandate" to maintain order and prevent violence.
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Pro-Morsi supporters rallied in eastern Cairo before security forces used tear gas and deadly force to clear the area.
The violence apparently began when the encampment of Muslim Brotherhood supporters tried to block a main road near Rabaah al-Adawiya Mosque in Cairo. Security forces moved in and street violence ensued.
Euronews reported that Muslim Brotherhood leader Mohammed al-Beltagi said that the group would not back down.
“We are staying here in peaceful protest.” he told the news agency.
“We have the right to stand in front of the world to say that all the people of Egypt have the right to choose their president, parliament and constitution. No military force has the right to one day wake up and suddenly decide who runs the government."
In the port city of Alexandria, pro and anti-Morsi demonstrators clashed overnight with nearly 200 injured and seven reported dead.
Former president Morsi has not been heard from since his ouster on July 3. He is being detained by the military and investigated on charges of espionage and aiding Hamas attacks against Egyptian police.
Twitter reacts to the ongoing violence: