Hundreds of people died, many of them shot, in the bloodiest day in decades in the Arab world’s biggest country.
The government said 235 people were killed and more than 2,001 injured, both in Cairo and in clashes that broke out elsewhere in the country. Deposed president Mohamed Morsi’s Muslim Brotherhood said the death toll was more than 2,000 in what it called a “massacre”.
Prime Minister David Cameron said the violence was “not going to solve anything”. He added: “What is required in Egypt is a genuine transition to a genuine democracy. That means compromise from all sides.”
As bodies wrapped in carpets were carried to a makeshift mortuary, the army-backed rulers declared a one-month state of emergency, restoring to the military the unfettered power it wielded for decades before 2011’s pro-democracy uprising.
Thousands of Mr Morsi’s supporters had been camped at two major sites in Cairo since before he was toppled on 3 July, and had vowed not leave the streets until he was returned to power.
Violence spread beyond Cairo, with Morsi supporters and security forces clashing in the cities of Alexandria and Suez, and in the Buhayra and Beni Suef provinces.
In a development that will worry Egypt’s Coptic Christians, who make up about 10 per cent of the population, churches were torched in Minya, Assiut, Sohag and the desert oasis
With the inevitable assault on the camps, the authorities have ended the six-week stand-off with a show of force that defied international pleas for restraint.
The bloodshed also effectively ends the open political role of the Brotherhood, which survived for 85 years as an underground movement before emerging from the shadows after the 2011 uprising to win every election held since.
In a rare sign of unease from among the Brotherhood’s opponents, Mohamed ElBaradei, the former United Nations diplomat, quit his post of vice-president in the army-backed government, saying that he was not prepared to be held responsible for a “single drop of blood” and that the conflict could have been resolved by peaceful means.
Since Mr Morsi was toppled, the security forces had twice before killed scores of protesters in an attempt to drive his followers off the streets. But they had held back from a full-scale assault on the tented camp where followers and their families have lived behind makeshift barricades.
After the assault on the camp began, desperate residents recited Koranic verse and screamed “God help us! God help us!”, while helicopters hovered overhead and armoured bulldozers ploughed over their defences.
The government insists people in the camp were armed.
Several television stations, all controlled by the state or its sympathisers, ran footage of what appeared to be pro-Morsi protesters firing rifles at soldiers from behind sandbag barricades.
However, to Western reporters, the crowds appeared to be armed mainly with sticks, stones and slabs of concrete against rifle-wielding police and troops.
The violence will force tough decisions on Egypt’s Western allies, especially Washington, which funds Egypt’s military with $1.3 billion a year and has refused to label its overthrow of Mr Morsi a “coup”. “The United States strongly condemns the use of violence against protesters in Egypt,” White House spokesman Josh Earnest said.
Mohamed El-Beltagi, Brotherhood leader, said his 17-year-old daughter had been killed in the clashes. Among the other dead were at least two journalists,
including British Sky cameraman Mick Deane, 61.
Mr Beltagi warned of wider conflict, and singled out the head of the armed forces Abdel Fattah al-Sisi who deposed Mr Morsi on 3 July, calling for his resignation. He added: “Abdel Fattah al-Sisi will push this nation to a civil war.”
Adli Mansour, the judge appointed president by the army last month, announced a state of emergency for one month and called on the armed forces to help police enforce security.
Human rights activists said the move would give legal cover for the army to make arrests.
Turkey urged the UN Security Council and Arab League to act quickly to stop a “massacre” in Egypt. Iran warned of the risk of civil war. The European Union and several of its member countries deplored the killings.
The government issued a statement saying security forces had showed the “utmost degree of self-restraint”, reflected in what it said were low casualties compared to the number of people “and the volume of weapons and violence directed against the security forces”.
Mr Morsi became Egypt’s first freely elected leader in June 2012, but failed to tackle a deep economic malaise and worried many Egyptians with apparent efforts to tighten Islamist rule.
Liberals and young Egyptians staged huge rallies demanding he resign, and the army said it removed him in response to the will of the people. Mr Morsi has been held at an undisclosed location since he was deposed.