Egypt’s bitter split over who should be ruling the country exploded into violent clashes in the streets of Cairo and elsewhere on Friday as masses of demonstrators celebrating the ouster of President Mohamed Morsi battled crowds of Islamists who wanted him reinstated.
Combatants used rocks, sticks, fireworks and Molotov cocktails in a battle lasting hours that raged near Tahrir Square and across a bridge spanning the Nile, part of the most widespread street violence in Egypt since the early days of the 2011 revolution.
The mayhem capped a day full of massive and defiant protests by Islamists demanding that Mr. Morsi be returned to power. At least four people were killed and many were wounded when security forces fired into a protest near the officers’ club of the powerful Republican Guard, where many believed Mr. Morsi was detained.
With clashes breaking out late into the night, it was impossible to estimate the full extent of casualties and damage. But early Saturday, security officials said at least 30 people had been killed nationwide and hundreds wounded, many of them in Cairo.
Islamists in other cities across the country also demanded Mr. Morsi’s reinstatement, breaking into government offices in several provinces and temporarily evicting military officials. Fifteen people died in Alexandria, and a curfew was declared in the Sinai Peninsula, where six soldiers and police officers were killed in at least four attacks on security posts.
The new violence suggested that the military’s removal of Mr. Morsi, the country’s first freely elected president, after protests by millions of Egyptians angry with his rule, had worsened the deep polarization between Islamists who call his ouster a military coup and their opponents who say his removal was the result of an urgent need to fix Egypt’s myriad problems.
By turning out in the tens of thousands, the pro-Morsi crowds underlined the organizational might of the Muslim Brotherhood, which emerged as the major political force and dominated rounds of elections after the country’s revolution two years ago. At that time, it gained power that many in the group had dreamed of for decades. The military’s intervention in politics this week entirely removed it from the government.
The group called the protests the “Friday of Rejection” and chanted for Mr. Morsi’s return.
“We will bring him back bearing him on our necks, sacrifice our souls for him,” Mohamed Badie, the group’s spiritual leader, told an enraged crowd at a large demonstration in the Cairo suburb of Nasr City. “We will bring back the rights of the Egyptian people who were wronged by this disgraceful conspiracy.”
Mr. Badie said the reports that he had been among the Islamist leaders arrested in a post-Morsi crackdown by security forces were false. Hundreds of Islamists were detained within a day after Mr. Morsi’s ouster. Some were released on Friday.
An interim president installed by the military, Adli Mansour, a former chief justice of the Supreme Constitutional Court, took a further step on Friday to erase the vestiges of Mr. Morsi’s government by formally dissolving the Shura Council, the country’s only operating house of Parliament, which the Islamists had dominated. The constitutional court had disbanded the lower house last year, one of many challenges Mr. Morsi had faced in his troubled tenure.
In a further affront to the Islamists, the Egyptian news media have marginalized their message in the two days since Mr. Morsi was deposed. Despite the interim government’s pledge of inclusiveness, Islamist television broadcasters were shuttered, and the state television barely covered the breadth of the pro-Morsi demonstrations on Friday.
Underpinning the Islamists’ fears of the emerging political order was a keen awareness of the long history of enmity with the security services. While some Islamists did use violence against the state, Egypt’s previous rulers kept even nonviolent Islamists in check by banning their organizations and subjecting them to arbitrary arrests and torture.
For some, those memories have come flooding back.
“They hung me up, they beat me, they used electricity — all the means of torture they had,” said Hussein Nada, 43, a protester, recalling the eight years he spent in prison for his association with the Gamaa al-Islamiyya, an ultraconservative Islamist group that attacked tourists and security forces in the 1990s but later renounced violence.
“Anyone from the opposition who came to power could decide to put us all back in prison,” he said. “As soon as the army came back, they put hundreds on the arrests list, so we fear we could lose all we’ve gained.”
The shooting outside the Republican Guard officers’ club broke out after protesters had reacted angrily to an officer who shredded a poster of Mr. Morsi that had been hung on the barbed wire blocking the entrance.
Blood spots stained the sidewalk where the wounded had fallen, and the size of the protest soon swelled as angry Islamists from elsewhere joined in.
“Where’s Morsi?” they screamed. Others denounced Egypt’s defense minister, Gen. Abdel-Fattah el-Sisi, who ordered Mr. Morsi’s removal on Wednesday. “Traitor, traitor, traitor! Sisi is a traitor!” they cried.
The clashes downtown erupted when masses of Mr. Morsi’s supporters marched across a Nile bridge to try to enter Tahrir Square, the epicenter of the uprising that toppled President Hosni Mubarak and the main spot for aggrieved Egyptians ever since. Anti-Morsi demonstrators, camped in the square, rushed to keep them out, and the two sides clashed on and around a bridge near the Ramses Hilton Hotel and the Egyptian Museum.
“This has become a gang war, a street battle,” said Hisham al-Sayyed Suleiman, 50, who stood watching the clashes from the bridge.
Military helicopters circled as the two sides faced off, each protecting its front line with huge sheets of metal. Rioters pelted each other with rocks and chunks of concrete and lobbed fireworks over their opponents’ heads, showering them with a rain of red, green and blue sparks.
The pro-Morsi rioters surged onto the bridge, and a battle raged over the Nile for hours until dozens of armored vehicles packed with black-clad riot police officers were deployed.
The anti-Morsi crowd hailed their arrival with cheers of “The people and the police are one hand!” and marched alongside as the armored convoy routed the Islamists off the bridge with blasts of birdshot and volleys of tear gas.
“They wanted to enter Tahrir so they could try to bring back Morsi, but we’ll never let that happen,” said Adel Ibrahim, 42, who carried a small satellite dish for a shield in one hand and stones in the other. “If the Islamists try to come back, we will all unite against them.”
Once the clashes subsided, dozens of young men climbed atop the police vehicles to cheers from the crowd. Some stopped to pose for photographs with police officers holding their shotguns — a curious sight since the police had been widely detested for killing protesters during the anti-Mubarak uprising.
Some said the police joining forces with Mr. Morsi’s opponents meant that the Muslim Brotherhood had lost its place in the country.
“They tried to rule the whole country for themselves,” said Ali Hassan, 32. “But if you want to rule Egypt, you have to rule for everyone or the people will stand against you.”
In a sign that the anti-Morsi backlash may have overreached, a Mubarak-appointed prosecutor general, Abdel Meguid Mahmoud, who had been dismissed by Mr. Morsi and was among those reinstated to his office on Thursday, resigned less than 24 hours later, apparently sensitive to the appearance of engaging in political retaliation. Mr. Mahmoud said in a statement that he had decided to resign to “avoid the embarrassment of making judicial decisions against those who removed me from office.”
The Obama administration, which provides $1.5 billion in annual aid to Egypt and has watched the crisis unfold with increased concern, called for calm. “We condemn the violence that has taken place today in Egypt,” Jennifer R. Psaki, a State Department spokeswoman, said in a statement. “We call on all Egyptian leaders to condemn the use of force and to prevent further violence among their supporters.”