Egyptians were on edge yesterday after supporters and opponents of ousted President Mohammed Morsi fought overnight in street battles that left at least 30 dead.
Cairo's emblematic Tahrir Square and nearby approaches to the River Nile were largely empty but left strewn with debris. Thousands of Morsi's Islamist supporters had marched to the area demanding his reinstatement but fled under a hail of stones, fireworks and gunfire.
Enraged at his overthrow by millions of protesters backed by the country's powerful military, tens of thousands of Morsi's supporters took to the streets on Friday, holding rallies they say they will continue until he is returned to office.
The chaotic scenes that played out in the capital, mostly on a bridge leading to Tahrir, ended only after the army rushed in with armoured vehicles to separate the warring groups.
The clashes accelerated after the supreme leader of Morsi's Muslim Brotherhood defiantly proclaimed his followers would not give up street action until the return of Egypt's first freely elected president.
"God make Morsi victorious and bring him back to the palace," Brotherhood chief Mohammed Badie proclaimed on Friday before cheering supporters at a Cairo mosque in his first appearance since the overthrow.
"We are his soldiers, we defend him with our lives."
Badie said it was a matter of honour for the military to abide by its pledge of loyalty to the president, in what appeared to be an attempt to pull it away from its leadership.
Hours later, his deputy, Khairat el-Shater, considered the most powerful figure in the organisation, was arrested in a Cairo apartment with his brother on allegations of inciting violence.
After the speech, a large crowd surged across 6th October Bridge over the Nile toward Tahrir, where a giant crowd of Morsi's opponents had been massed all day.
Battles broke out there and near the neighbouring state TV building.
Pro-Morsi youth shielded themselves from flying stones and fireworks with sheets of metal. A car burned at the top of an exit ramp amid the sounds of automatic weapons and shotguns.
At least three people were killed at the bridge.
Throughout the country, clashes erupted as Morsi supporters tried to storm local government buildings or military facilities, battling police or Morsi opponents.
Besides the 30 killed throughout the day, 210 were wounded, said Health Ministry official Khaled el-Khatib.
Islamists descended on an anti-Morsi rally, opening fire with guns in the Mediterranean coastal city of Alexandria, where at least 12 people - mostly Morsi opponents - were killed.
One man was stabbed and thrown from the roof of a building by Morsi supporters after he raised an Egyptian flag and shouted insults against the ousted president.
Security officials said militants killed five policemen in shootings around the Sinai city of el-Arish.
The US State Department condemned the violence and called on all Egyptian leaders to denounce the use of force and prevent further bloodshed.