Egyptian police have used tear gas and water cannon to break up rare anti-government protests in the capital.
Thousands of people had joined the protests in Cairo, inspired by the recent uprising in Tunisia, vowing to stay until the government fell.
Three people died during Tuesday's nationwide internet-inspired "day of revolt", which the government blamed on a banned opposition movement.
Some protesters began gathering again early on Wednesday in central Cairo.
However, there is no sign yet of the huge police presence that's usually fielded when demonstrations are expected, the BBC's Jon Leyne reports from Cairo.
Protests are uncommon in Egypt, which President Hosni Mubarak has ruled since 1981, tolerating little dissent.
In Washington, the White House urged the Egyptian government to allow protests to go ahead, describing the situation as "an important opportunity" for the nation.
France's foreign minister said she regretted the loss of life in Egypt but said democracy should be encouraged in all countries around the world.
Tuesday's event had been co-ordinated on a Facebook page, where the organisers said they were taking a stand against torture, poverty, corruption and unemployment.
They said that the rally would mark "the beginning of the end".
Our correspondent said that it had been unclear how many people would respond to the online call, but in the end, the turnout was more than the organisers could have hoped.
Police were taken aback by the anger of the crowd and let protesters make their way to Tahrir Square near the parliament building, he says.
Opposition organisers urged a repeat demonstration on Wednesday, the AFP news agency reported.
Microblogging site Twitter also played a key part, with supporters inside and outside Egypt using the search term #jan25 to post news of the day.
However, Twitter confirmed later on Tuesday that it had been blocked inside Egypt from 1600 GMT, meaning many were unable to post updates from the scene.
"We believe that the open exchange of information and views benefits societies and helps governments connect with their people," Twitter said on its official account.
'Mubarak the coward'
The crowds' anger was largely focused on the president, with thousands calling for his resignation and "Down with Mubarak" scrawled on the walls of buildings.
Those gathered vowed to stay in the square until Egypt's government had fallen.
But at 0100 local time (2300 GMT Tuesday) police moved in, firing tear gas and driving protesters into nearby streets. There were reports that some people had been beaten by police.
"It got broken up ugly with everything, shooting, water cannon and [police] running with the sticks," one of the last protesters to leave, Gigi Ibrahim, told the Associated Press.
"It was a field of tear gas. The square emptied out so fast."
State TV said one policeman had died in clashes.
As dawn neared, Tahrir Square was reported to be empty of demonstrators, with cleaners removing rocks and litter as police looked on. But our correspondent said some returned as Cairo began its working day.
Protests were also held out in other areas of the country on Tuesday, including the eastern city of Ismailiya.
Thousands joined protests in the northern port city of Alexandria, some chanting: "Revolution, revolution, like a volcano, against Mubarak the coward."
Two protesters died in Suez, doctors there said.
In Washington, the White House said Egypt's government had "an important opportunity to be responsive to the aspirations of the Egyptian people".
In a statement, it said Egypt should "pursue political, economic and social reforms that can improve their lives and help Egypt prosper."
"The United States is committed to working with Egypt and the Egyptian people to advance these goals," it added.
US Secretary of State Hillary Clinton said her administration supported "the fundamental right of expression and assembly" and urged all parties "to exercise restraint".
She added that Washington believed the Egyptian government was "stable" and "looking for ways to respond to the legitimate needs and interests of the Egyptian people".
The Egyptian government said it had allowed the protesters "to voice their demands and exercise their freedom of expression".
It blamed the violence on the banned Islamist movement the Muslim Brotherhood, saying its supporters "began to riot, damage public public property and throw stones at police forces".
However, our correspondent says that one opposition leader, Mohamed ElBaradei, had called on Egyptians to take part in these protests, the Muslim Brotherhood had been more ambivalent.
Tunisia's President Zine al-Abidine Ben Ali was ousted from power and fled the country earlier this month, after weeks of protests in which dozens of people were killed.
Egypt has many of the same social and political problems that brought about the unrest in Tunisia - rising food prices, high unemployment and anger at official corruption.
However, the population of Egypt has a much lower level of education than Tunisia. Illiteracy is high and internet penetration is low.
There are deep frustrations in Egyptian society, our Cairo correspondent says, yet Egyptians are almost as disillusioned with the opposition as they are with the government; even the Muslim Brotherhood seems rudderless.
Our correspondent adds that Egypt is widely seen to have lost power, status and prestige in the three decades of President Mubarak's rule.