The Egyptian capital Cairo is reported quiet after a crackdown on Islamists which left hundreds dead and drew international condemnation.
At least 327 people died when security forces stormed two camps which supporters of ousted leader Mohammed Morsi set up in the city last month.
A state of emergency was declared and curfews imposed in Egyptian cities.
US Secretary of State John Kerry said the “deplorable” events were “a real blow to reconciliation efforts”.
EU foreign policy chief Catherine Ashton and UN Secretary-General Ban Ki-moon also criticised the use of force.
Egyptians are waking up to a frightening and uncertain future, the BBC’s Bethany Bell reports from Cairo.
Even after the curfew was lifted on Thursday morning, there was very little traffic out on the central streets and the bridges across the Nile, she says.
Aerial footage showed multiple fires on Cairo’s streets yesterday
The demonstrators had been demanding the reinstatement of Mr Morsi, who was removed by the military on 3 July.
The Muslim Brotherhood, which backed the sit-ins in Nahda Square and near the Rabaa al-Adawiya mosque, says the true number of people killed on Wednesday is more than 2,000.
According to the military-backed interim government, at least 43 police officers are among the dead. A further 2,926 people were injured.
The Muslim Brotherhood is likely to continue with its protests, says the BBC’s Middle East editor, Jeremy Bowen.
They waited 80 years to take power in Egypt and they feel that power was taken away from them unjustly, he adds.
Mr Kerry said Egypt’s political reconciliation efforts had suffered a “serious blow”.
“This is a pivotal moment for all Egyptians,” he added. “The path toward violence leads only to greater instability, economic disaster and suffering.”
The office of UN chief Ban Ki-moon said he regretted that the Egyptian authorities had chosen to use force while “the vast majority of the Egyptian people want their country to go forward peacefully in an Egyptian-led process towards prosperity and democracy”.
“Strongly” condemning the violence, Mrs Ashton said that “only a concerted effort by all Egyptians and the international community might lead the country back on a path to inclusive democracy, and overcome Egypt’s challenges”.
In other reaction
Turkish Prime Minister Recep Tayyip Erdogan has called for an urgent meeting of the UN Security Council to discuss a “very serious massacre”
British Prime Minister David Cameron said the violence was “not going to solve anything” and there needed to be “compromise from all sides”
Germany said Wednesday’s events were a “very dangerous” escalation of violence
France demanded an “immediate end to the repression”
In a televised address, Egyptian Interim Prime Minister Hazem Beblawi defended the operation, saying the authorities had to restore security.
Expressing regret for the loss of life, he said the state of national emergency would be lifted as soon as possible.
The measure imposes a curfew in Cairo and several other provinces between 19:00 local time (17:00 GMT) and 06:00.
Interior Minister Mohammed Ibrahim said the police had “dealt professionally” with the protesters, and accused the pro-Morsi protesters of firing birdshot at police.
Following the violence, Vice-President Mohammed ElBaradei announced his resignation from the interim government, saying he could not “shoulder the responsibility for a single drop of blood”.
Reports said the smaller camp in Nahda Square was cleared quickly but clashes raged for several hours around the main camp near the Rabaa al-Adawiya mosque.
Mobs later carried out reprisal attacks on government buildings and police stations as well as churches belonging to the country’s Coptic Christian minority.
Egyptian TV said that by evening the security forces had seized full control of the site, and were allowing protesters there to leave.
But several Muslim Brotherhood leaders were reportedly detained, including Essam El-Erian and Mohamed El-Beltagi.
Speaking before his reported arrest, Mr Beltagi said his daughter Asmaa, 17, had been killed in the clashes.
Three members of the media were killed: Sky News cameraman Mick Deane, Gulf News reporter Habiba Ahmed Abd Elaziz (who was not working at the time) and Ahmed Abdel Gawad, who wrote for Egyptian state-run daily Al-Akhbar.
Mr Morsi – Egypt’s first freely elected president – is currently in custody at an undisclosed location, accused of murders during a prison breakout in 2011.