Update at 12:36 p.m. ET: Protesters on the streets of Cairo are trying to storm the Egyptian Foreign Ministry and the state TV building, the Associated Press reports. The headquarters of the President Hosni Mubarak's ruling National Democratic Party has been set afire.

Mubarak, who has deploy the army to impose a nationwide 6 p.m. to 7 a.m. curfew, is to address the nation short on television, the AP says.

The curfew was initially imposed only for Cairo, Alexandria and Suez, but within 3 hours was expanded nationwide, state TV reports.

Update at 11:30 a.m. ET: The headquarters of Egypt's ruling NDP party has been set on fire, Reuters and AlJazeera TV report. The flames began erupting not long after a curfew was imposed on Cairo and two other Egyptian cities.

Update at 11:13 a.m. ET: Crowds of protesters in Cairo set a police car on fire and try to dump it into the Nile, AlJazeera reports.

In Suez, AlJazeera reports, army tanks have been deployed in the streets to try to impose a 6 p.m.-7 a.m. (local time) curfew.

Update at 10:49 a.m. ET: Embattled Egyptian President Hosni Mubarak is preparing to speak to the nation, which is undergoing unprecedented protests by tens of thousands of people.

Mubarak has also ordered the army into the streets to impose a curfew in Cairo, Alexandria and Suez in the face of major protests by tens of thosuands of people.

The curfew began at 6 p.m. (11 a.m. ET) and is to last until 7 a.m.

Click here to watch dramatic coverage in English from AlJazeera.

In addition, opposition leader and Nobel laureate Mohamed ElBaradei has been place under house arrest, the Associated Press reports, quoting security officials.

ElBaradei, the former head of the U.N. nuclear watchdog agency, returned to Cairo on Thursday evening, saying he would join protesters on the street. He attended Friday prayers today and was in the middle of skirmishes with riot police.

Another opposition figure, Ayman Nour, was hit by a rock during the demonstration and taken to the hospital, his son tells AlJazeera TV. His son says his father was "semi-conscious" when he was hospitalized. Nour, a former member of the Egyptian Parliament and chairman of the El Ghad party, was jailed in 2005 for his opposition activity.

Update at 8:33 a.m. ET: A senior member of Egypt's ruling NDP party tells AlJazeera's English language broadcast that "this government will never continue anymore."

The unidentified official says the protesters include lots of young people "with no political agenda."

He says he expects President Hosni Mubarak to address the crisis in coming days and institute major reforms.

The official calls the situation "unprecedented" and says it calls for an untraditional response. He says it is "not a sign of weakness" to respond to the demands of demonstrators.

"This is a moment of wisdom and Egypt has to take action against corruption, against poverty, upgrading the standard of living of people, giving more freedoms," he says. "This should be considered now more than ever."

Earlier posting: AlJazeera English is offering some of the best live coverage of the protests in Egypt where tens of thousands of demonstrators are clashing with police with batons and water cannons.

AlJazeera says some parts of the capital are in "complete lockdown." Almost all Internet traffic to Egypt has been cut off in an apparent effort by authorities to disrupt protest organizers.

AlJazeera reports clashes in at least seven cities in Egypt, including Alexandria and Giza.