Dozens of people were wounded as police and demonstrators fought running street battles in Cairo on Friday in unprecedented protests against President Hosni Mubarak's three-decade rule.
Security forces fired rubber bullets, teargas and water cannon at the crowds and baton charged them. The protesters hurled stones back and shouted "Down, Down, Hosni Mubarak."
Witnesses saw dozens of Egyptians bruised, bloodied and fainting. Al Jazeera television said at least one person was killed in a square in central Cairo, although the report could not be confirmed.
Tens of thousands of Egyptians took to the streets after Friday prayers in by far the biggest of four consecutive days of protests by people fed up with unemployment, poverty, corruption and the lack of freedom under Mubarak.
"They (the government) want to destroy the whole country to keep one man in power," one protester shouted as he ran from police.
Such popular unrest has not previously been seen during Mubarak's rule of Egypt, where security services keep a tight grip on dissent.
It was triggered by the overthrow two weeks ago of Tunisian President Zine al-Abidine Ben Al Ben Ali in a popular revolt which also inspired anti-government protests in Yemen.
The events pose a quandary for the United States, which has professed its wish for democracy to spread across the Middle East. Mubarak, however, has been a close Washington ally for many years and the recipient of huge amounts of military aid.
In response to the protests, US President Barack Obama said social and political reforms in Egypt were "absolutely critical".
Confrontations broke out all over central Cairo between groups of demonstrators and police on Friday, witnesses said.
Snatch squads of plain clothes securitymen dragged off suspected ringleaders. At the Fatah mosque in central Ramses Square, several thousand people were penned in and teargassed.
Protesters often quickly dispersed and regrouped.
Some held banners saying: "Everyone against one" and chanted "Peaceful peaceful peaceful, no violence." Others threw shoes at and stamped on posters of Mubarak. But as the clashes intensified, police waded into the crowds with batons and fired volleys of teargas.
"Leave, leave, Mubarak, Mubarak, the plane awaits you," people chanted.
One car was set ablaze and some police cars were surrounded and attacked by protesters, witnesses said.
Prominent activist Mohamed ElBaradei, a Nobel Peace Laureate, was briefly penned in by police after he prayed at a mosque in the Giza area but he later took part in a peaceful march with supporters. Arabiya television said later police had "asked" him to stay home but this could not be confirmed.
In Alexandria, protesters overran police lines and torched police trucks, a witness said.
In several cities, protesters stormed the offices of the ruling National Democratic Party, witnesses reported. In Damietta, on the north coast, protesters ransacked the local council offices.
In some parts of Cairo, protests were peaceful. Dozens of people prayed together on one road. In Giza, on the city outskirts, marchers shook hands with the police who let them pass peacefully.
YOUNG AND RESTLESS
Before Friday's clashes, at least five people have been killed over the four days, one of them a police officer. Police have arrested several hundred people.
Members of the Muslim Brotherhood opposition group, including at least eight senior officials, were rounded up overnight. The government has accused the Brotherhood of planning to exploit the youth protests while it says it is being made a scapegoat.
Internet via Egyptian servers had been blocked across the country after midnight, closing a key tool for activists relying on social media networks to spread word. Mobile phone and text messaging services appeared to be disabled or working sporadically.
Many protesters are young men. Two thirds of Egypt's 80 million people are below the age of 30 and many have no jobs. About 40% of Egyptians live on less than $2 a day.
Egypt has been under emergency rule throughout Mubarak's term in office. The government says it is used to combat terrorism. Critics say it is used to stifle any dissent.
Elections were due to be held in September and until now few had doubted that Mubarak would remain in control or bring in a successor in the shape of his 47-year-old son Gamal.
Father and son deny that Gamal is being groomed for the job.