Nearly 280 people have been reported killed and some 2,000 injured in violence that broke out across Egypt as security forces dismantled protest camps in Cairo set up by supporters of ousted President Muhammad Morsi.
Authorities said the death toll included 235 civilians and 43 members of the security forces.
The Muslim Brotherhood, of which the deposed president is a senior leader, said the death toll was far higher.
The military-backed authorities have announced the start of a one-month nationwide state of emergency in the wake of the August 14 bloodshed.
Muhammed ElBaradei, the Nobel Peace Prize laureate, has resigned as vice president in the interim government in protest.
State TV says the largest protest camp, at Cairo's Rabaa al-Adawiya Mosque, was cleared after Morsi supporters were given safe passage following a daylong clash. A smaller protest camp was cleared earlier in the day.
A statement from the presidency read out on state television said interim President Adli Mansour had asked the army to back the police in maintaining security and protecting people's lives.
The United States has condemned the violence against protesters and says it opposes the state of emergency.
"We have repeatedly called on the Egyptian military and security forces to show restraint and for the government to respect the universal rights of its citizens, just as we have urged protesters to demonstrate peacefully," deputy White House spokesman Josh Earnest said.
"Violence will only make it more difficult to move Egypt forward on a path to lasting stability and democracy and runs directly counter to the pledges by the interim government to pursue reconciliation."
The White House also urged all sides in Egypt to refrain from violence and resolve their differences peacefully.
U.S. Secretary of State John Kerry said in Washington that all Egyptian parties should avoid violence and "participate in the path toward a political solution." He also called on Egypt's military to hold elections.
The United Nations, the European Union and a number of nations have also urged restraint.
Morsi, a prominent member of the Muslim Brotherhood, was ousted and detained by the military on July 3 following huge popular protests against him.
Security forces backed by armored vehicles and bulldozers moved on the camps using tear gas and reportedly firing live ammunition.
Protesters kept chanting after being forced out of the square.
WATCH: Morsi supporters defiant as Egyptian forces clear camps.
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The security operation against the larger camp outside the Rabaa al-Adawiya Mosque in the Nasr City neighborhood of the Egyptian capital appeared to meet with more resistance.
Security forces reportedly opened fire on stone-throwing protesters who were trying to join those already in the cordoned-off camp, where several Muslim Brotherhood leaders were staying.
Live broadcasts from the area showed large plumes of smoke and tear gas rising from a bridge overlooking the Rabaa al-Adawiya Mosque, while helicopters hovered over the site.
Clashes Across Egypt
Deadly clashes between protesters and police were reported in several other cities. The Muslim Brotherhood has urged Egyptians to take to the streets to "stop a massacre."
There were reports of clashes in the cities of Minya and Assiut between Islamist protesters and security forces on August 14.
Security forces fired tear gas at thousands of Morsi supporters who had set part of a church on fire in Minya. In Assiut, about 3,000 Morsi supporters clashed with police.
PHOTO GALLERY: Violence flares in Cairo clashes.
Violence Flares In Cairo As Forces Clear Protest Camps
State television said more than 200 people were arrested, some allegedly carrying light weapons. Rail services across Egypt were suspended, reportedly to prevent pro-Morsi supporters from converging on Cairo.
During the Cairo violence, Mick Deane, a cameraman for British news channel Sky News was shot dead, while a Voice of America reporter was pulled from a car and briefly detained by police.
The government issued a statement saying security forces had showed the "utmost degree of self-restraint."
The government, which has pledged to hold new elections in about six months to return democratic rule to Egypt, urged the protesters not to resist the authorities, adding that Muslim Brotherhood leaders must stop inciting violence.
Appeals For Restraint
International reaction to the crackdown came quickly.
The European Union called on all sides to show restraint. "Let me reiterate the EU's position that the violence does not lead to any solutions and that is why we are urging strongly all parties to exercise maximum restraint," EU spokesman Peter Stano said.
Michael Mann, a spokesman for EU foreign-policy chief Catherine Ashton, said reports of deaths and injuries "are extremely worrying."
Meanwhile, German Foreign Minister Guido Westerwelle urged Egypt's interim government and Morsi's backers to avoid further bloodshed.
"We appeal to all political forces to return to dialogue and negotiations and avoid an escalation of the violence," he said. "Any further spillage of blood in Egypt must be prevented. We call on all sides to return to a political process that includes all political forces."
British Foreign Secretary William Hague said in a statement that he was "deeply concerned" about the situation in Egypt.
UN Secretary-General Ban Ki-moon has strongly condemned violence used by security forces against protesters. His spokesman said Ban also called on all sides to work toward a peaceful reconciliation.
Turkish President Abdullah Gul told reporters in Ankara that armed intervention against Egyptian protesters was "completely unacceptable." Prime Minister Recep Tayyip Erdogan's office also called on the UN Security Council and the Arab League, to act "immediately to halt the crackdown."
Turkey's Islamist-rooted government has emerged as one of the most vocal critics of what it has called an "unacceptable coup" after Egypt's military ousted Morsi, who was elected as president in June 2012.