Witnesses said a crowd of at 10,000 people was moving east from Cairo’s Mohandeseen neighborhood, trying to reach the central Tahrir Square that has been an epicenter of protest. But police lobbed tear-gas to try to prevent people from reaching the square. Some demonstrators stamped on photographs of the president and others chanted “Down, down with Mubarak.”
Near Al Azhar mosque in old Cairo, thousands of people flooded onto the streets after noon prayers chanting “The people want to bring down the regime.” Police fired tear-gas and protesters hurled rocks as they sought to break though police lines. From balconies above the street, residents threw water and lemon to protesters whose eyes were streaming with tear gas.
Similar demonstrations were also reported in the cities of Suez, Alexandria and several others, including Al Arish in northern Sinai.
According to The Associated Press, police doused one of the most prominent opposition figures, Mohammed ElBaradei, with a water-cannon and beat supporters who tried to shield him. Mr. ElBaradei, the former head of the International Atomic Energy Agency, returned to Cairo on Thursday, promising to join the largely leaderless protests that have so far been propelled by young people. Internet and cellphone connections have been closed or restricted in Cairo, Alexandria and other places, cutting off social media Web sites that had been used to organize protests and complicating efforts by news media to report on events on the ground. Riot police took to the streets of Cairo before the Friday noon prayers that in many parts of the Islamic world have been a prelude to unrest as worshippers pour onto the streets.
The protests have underscored the blistering pace of events that have transformed the Arab world, particularly among regimes that have traditionally enjoyed the support of successive administrations in Washington.
Earlier this month, entrenched autocracies seemed confident of their ability to ride out the protests. But, just two weeks ago, on Jan. 14, President Zine el-Abidine Ben Ali of Tunisia fled abruptly into exile after weeks of protest and his departure emboldened demonstrators to take to the streets in other countries.
Images of the lowly challenging the mighty have been relayed from one capital to the next, partly through the aggressive coverage of Al Jazeera, the Qatar-based satellite channel. Social networking sites such as Facebook and Twitter have given the protesters a potent weapon, enabling them to elude the traditional police measures to monitor and curb dissent. But various regimes have fallen back on a more traditional playbook, relying on security forces to face angry demonstrators on the streets.
In Cairo’s central Tahrir Square, a focal point of protest, reporters on Friday saw black-uniformed riot police taking up position, pouring from armored trucks, and protesters said several members of the outlawed Muslim Brotherhood, the largest opposition organization, had been arrested overnight.
The police presence in Alexandria on the Mediterranean coast was strongest in the center of the city. At the Sidi Bishir mosque outside the center of town, a dozen men wore Egyptian flags wrapped around their shoulders. With cellphone and Internet connections down, activists across the city tried to determine the extent of arrests overnight by security officials.
“Our plan is to march from all the mosques,” said Mustafa Mohammed, 54, a former parliamentarian from Alexandria. “We do not know if we’ll be able to march, but there will be protests.”
Ibrahim Abdelkhaled, 25, a mobile-phone repairman, said: “The government is trying their level best to make sure these protests don’t happen. But we already agreed on the place yesterday. We expected them to try to shut down the networks.”
He added, “We’re here because we’re demanding the resignation of Mubarak and his government because after 30 years we are all fed up with him. We will march in the streets so that he leaves.”
On Thursday, the Muslim Brotherhood, which had remained formally aloof from the earlier protests, seemed to be seeking to aligning itself with the youthful and apparently secular demonstrators, saying it would support Friday’s protests. Mohamed ElBaradei, the former head of the International Atomic Energy Agency and an opposition leader, returned from Vienna saying he would join protests, whose passion and scale had taken him by surprise.
Also on Thursday, thousands of protesters took to the streets of Yemen, one of the Middle East’s most impoverished countries, demanding the ouster of the 32-year-old American-backed government of Ali Abdullah Saleh, vowing to continue until the government either fell or consented to reforms.
At least visually, the scenes broadcast across the region from Yemen were reminiscent of the events in Egypt and the month of protests that brought down the government in Tunisia. But as they climaxed by midday, they appeared to be carefully organized and mostly peaceful, save for some arrests. Pink — be it in the form of headbands, sashes or banners — was the dominant color; organizers described it as the symbol of the day’s protests.
The Yemeni protests were another moment of tumult in a region whose aging order of American-backed governments appears to be staggering, confronting movements with divergent goals but access to similar technology.
Documents made available by the WikiLeaks antisecrecy group, for instance, offered protesters in Tunisia documentary evidence in confidential American diplomatic communications of the opulent lifestyle of Mr. Ben Ali’s family.
On Thursday, protesters in Tunisia’s scored a new victory when the interim government purged almost all the cabinet ministers left over from Mr. Ben Ali’s administration.
Prime Minister Mohamed Ghannouchi, Mr. Ben Ali’s former right-hand man, announced the changes in a televised address, but did not resign. He reiterated a pledge to guide the country to free and fair elections within six months and then retire from government. “This is a temporary government with a clear mission — to allow a transition to democracy,” Mr. Ghannouchi said. Another trove of dispatches made public by WikiLeaks paints a vivid picture of the delicate dealings between the United States and Egypt, its staunchest Arab ally. They show in detail how diplomats repeatedly raised concerns with Egyptian officials about jailed dissidents and bloggers, and kept tabs on reports of torture by the police.
But they also reveal that relations with President Hosni Mubarak warmed up because President Obama played down the public “name and shame” approach of the Bush administration.
Reporting was contributed by David D. Kirkpatrick, Karim Faheem, Mona El-Naggar and Dawlat Magdy in Cairo; Nicholas Kulish and Souad Mekhennet in Alexandria, Egypt; Anthony Shadid and Nada Bakri in Beirut, Lebanon; and Mark Landler and Andrew W. Lehren in Washington.