Egyptian security forces have stormed two protest camps occupied by supporters of deposed president Mohammed Morsi in Cairo, with reports of many killed.
Witnesses said they saw at least 40 bodies, but the Muslim Brotherhood says hundreds died.
Armoured bulldozers moved deep into the main camp outside the eastern Rabaa al-Adawiya mosque.
Officials say the other protest camp, at Nahda Square, has also been cleared.
Graphic accounts of bloodshed emerged from the protest camps as reporters described wounded protesters being treated next to the dead in makeshift field hospitals.
The 17-year-old daughter of leading Muslim Brotherhood figure Mohamed el-Beltagy was among the dead. Asmaa el-Beltagy was shot in the back and chest, her brother said.
A cameraman working for Sky News, Mick Deane, has also been killed in the violence.
There were reports of unrest elsewhere in Egypt.
- At least five people have been killed in the province of Suez, according to the health ministry. Witnesses say Morsi supporters attempted to storm government buildings there
- Clashes have also been reported in the northern provinces of Alexandria and Beheira, and the central provinces of Assiut and Menya
- Hundreds are said to have gathered outside the governor's office in Aswan in the south
- Morsi supporters are reported to have blocked roads in Alexandria
- State news agency Mena says three churches were attacked in central Egypt, one in the city of Sohag with a large number of Coptic Christian residents
The interior ministry said a mopping-up operation in the streets surrounding Nahda Square was under way. Pro-Morsi activists were chased into the nearby zoo and Cairo University, Nile TV said.
It is still unclear how many casualties were caught up in the two Cairo operations. Figures differ widely and have been impossible to verify independently.
Western journalists said they saw at least 40 bodies in a makeshift morgue at the protest site at the Rabaa al-Adawiya mosque.
Ikhwanonline, the website of the Muslim Brotherhood, which supports the protests, says more than 800 were killed.
The health ministry has issued an official death toll of 56.
The interior ministry denied any deaths were caused by its forces firing live ammunition.
"Security forces used only tear gas canisters to disperse the protesters though it was heavily fired at by armed elements from inside the two protest camps, causing the death of an officer and a conscript and the injury of four policemen and two conscripts," the ministry said in a statement.
The government has meanwhile congratulated the security forces on their operation to clear the camps.
In a televised statement, a government spokesman praised their "self-restraint" and spoke of the "smaller number" of injuries among protesters.
The government would decisively confront attempts to attack state buildings and police stations, he said.
Supporters of Mr Morsi have been occupying Nahda Square and the Rabaa al-Adawiya site since he was ousted on 3 July. They want him reinstated.
Large plumes of smoke rose over parts of the city as the operation to clear the camps began, with tear gas canisters fired and helicopters hovering above.
Muslim Brotherhood TV called for people to send cars to the sit-ins to take casualties to hospital.
Several Muslim Brotherhood figures have been arrested, security sources said.
The protesters had been expecting the clearance operation, says BBC Middle East editor Jeremy Bowen.
It is a heavy-handed operation and is a consequence of the current "winner takes all" climate, he adds, with both sides sticking to their positions and pushing as hard as they can.
Call for restraint
There has been strong international reaction to the storming of the camps.
The European Union called the reports of deaths and injuries "extremely worrying".
A statement issued on behalf of EU foreign policy chief Catherine Ashton said: "We reiterate that violence won't lead to any solution and we urge the Egyptian authorities to proceed with utmost restraint."
Turkish PM Recep Tayyip Erdogan described the result of the camp clearances as a massacre, accused other countries of paving the way for the violence by staying silent, and called for the UN and the Arab League to act immediately.
UK Foreign Secretary William Hague also condemned the use of force.
More than 250 people have been killed in clashes with the security forces in the six weeks since Mr Morsi's overthrow.
Speaking to the BBC on Monday, Egypt's Foreign Minister Nabil Fahmy said the sit-ins could not continue "endlessly".
He said the authorities had been trying to seek an agreement through dialogue.
"If the police force take their procedures, they will do that in accordance with the law by court order and in accordance to the basic norms on which these things are done."