Tens of thousands of defiant Muslim Brotherhood supporters thronged Egypt's streets today for "Friday of anger" protests as at least five persons were killed in fresh clashes after 638 people died in a brutal crackdown on supporters of ousted president Mohammed Morsi.
Four pro-Morsi protesters were shot dead in clashes with security forces in the Suez Canal city of Ismailia, while the state media reported that a policeman was killed in an armed attack on a Cairo checkpoint.
Violence was also reported from different parts of the deeply polarised country, even as military vehicles were deployed across Cairo and Giza, taking up positions in squares and securing important institutions, the state-run EGYNews reported.
The Egyptian army tightened security in Cairo and other cities in response to the Muslim Brotherhood's calls for marches from 28 mosques following Friday prayers.
Tens of thousands of pro-Morsi supporters took to the streets after Friday prayers for marches as part of what they dubbed as a "Friday of anger" in defiance of the military-imposed state of emergency.
Armoured vehicles and barbed wires blocked all entrances to Tahrir Square, and 22 armoured vehicles were in Mustafa Mahmoud Square.
Security forces fired birdshot and tear gas to stop supporters from reaching a government building in the northern Egyptian city of Tanta.
The Muslim Brotherhood had promised huge protests today, and Egypt's military government showed no sign of easing its crackdown, setting the stage for what could become another catastrophic encounter of security forces and protesters.
"The struggle to overthrow this illegitimate regime is an obligation," the Muslim Brotherhood said on its website today, while urging people to protest peacefully.
The state-run media said the military increased checkpoints at all entrances to Cairo to prevent arms smuggling to protesters.
Also today, at least 20 police officers were wounded when assailants opened fire on two security cars north of Cairo.
The announcement to hold protests came after at least 638 people were killed when security forces cleared two pro-Morsi protest camps at Rabaa al-Adaweya and al-Nahda, ending sit-ins that began after the army toppled Morsi on July 3.
The health ministry spokesman yesterday said death toll from nationwide violence in Egypt has climbed to 638, making it the bloodiest day since the Arab Spring in 2011 toppled longtime President Hosni Mubarak in a popular uprising.
"Anti-coup rallies tomorrow will depart from all mosques of Cairo and head towards Ramsis square after Jumaa prayer in 'Friday of Anger'," Muslim Brotherhood spokesman Gehad el-Haddad wrote on his Twitter account yesterday.
Officials from the Muslim Brotherhood have said the death toll was eight or nine times higher than the government figures.
Muslim Brotherhood said it suffered a strong blow from the state security crackdown and the bloodshed means anger is now "beyond control".
Meanwhile, Egypt spent its first day under emergency rule and curfew yesterday, with Cairo remaining tense and bracing for further unrest.
But, defiant Morsi supporters attacked the local government offices in Giza and set them ablaze. Television footage showed the headquarters in flames as men tried to douse the fire with hoses. Assailants used Molotov bombs to burn down the building.
There were also reports of clashes in Ma'adi, a neighbourhood in southern Cairo, between local residents and Morsi supporters, with witnesses saying both sides exchanged gunfire.
The army-backed interim government has defended the crackdown, saying authorities had no choice but to act.
Defying criticism from major Western allies, Egypt's government warned it would turn its guns on anyone who attacked the police or public institutions after protesters torched a government building in Cairo.
Leftist coalition, the National Salvation Front, also called on Egyptians to protest against what it said was "obvious terrorism actions" conducted by the Muslim Brotherhood.
Warning that Egypt had entered a "more dangerous path", President Barack Obama cancelled US military exercises with the Arab country to protest the killing of hundreds of Egyptian protesters.
"We deplore violence against civilians. We support universal rights essential to human dignity, including the right to peaceful protest," he said. The Egyptian presidency issued a statement saying Obama's remarks were not based on facts and would strengthen and encourage violent groups that were committing "terrorist acts."