Dozens of people have reportedly been killed in fresh clashes between police and protesters across Egypt.
Violence erupted as demonstrators took to the streets at the end of Friday prayers in the wake of the midweek bloodbath when troops cleared pro-Morsi protest camps.
In Cairo thousands of supporters of ousted president Mohamed Morsi converged on Ramses Square in defiance of the military-imposed state of emergency.
Security forces blocked roads leading to the square, and violence broke out, the BBC reported.
Pro-Morsi demonstrators hurled stones at a police station and security forces responded with teargas and live ammunitions. Clashes between civilians supporting the military-backed interim government and Muslim Brotherhood demonstrators were also reported and there was fighting in other Egyptian towns and cities.
At least 13 people have been killed, according to Reuters.
"A lot of casualties are being ferried out from the square on bikes and scooters. I've seen several people who have been shot through the head," BBC Middle East editor Jeremy Bowen said.
Street fights broke out in other parts of town. An explosion and gunfire were reported near the Four Seasons hotel on the banks of the Nile River.
Security said that eight people were killed in the Nile Delta province of Dumyat north of Cairo and another four died in the Suez Canal city of Ismailiya.
Five policemen were killed across the country, officials said.
Another five civilians were killed in the city of Fayoum, south of Cairo, a hospital official told Reuters.
Demonstrators were responding to the Muslim Brotherhood's call for a "Friday of Anger", following the deaths of at least 638 people on Wednesday when riot police backed by armoured vehicles, snipers and bulldozers smashed two sit-ins in the capital.