Anti-government protesters in Egypt have fought back against supporters of President Hosni Mubarak, pushing them out of some streets in central Cairo which they controlled.
Stones were thrown on both sides, and some gunshots have been heard.
The army, which was trying to separate the two sides, appears to have failed to control the crowds.
The clashes came as the vice-president said Mr Mubarak's son Gamal would not stand for president.
In a TV address on Tuesday, President Mubarak said he would stand down at presidential elections later this year, but said nothing about his son.
Earlier PM Ahmed Shafiq apologised for the fighting, which has killed nine and wounded hundreds.
He pledged to investigate the violence, calling it a "disaster".
The protesters are demanding that Mr Mubarak, who has ruled for 30 years, step down immediately.
The BBC's Jeremy Bowen in Tahrir Square says they are now more determined than ever.
The square looks for the first time like a revolutionary scene, with barricades, flags and men with bandages around their heads, he adds.
Tension is also high in the second city, Alexandria, where one of the country's largest shopping malls has been ransacked by looters.
'Great destruction'
Separately, there were reports of attacks on foreign journalists, with Mubarak supporters said to have stormed a number of Cairo hotels.
Some journalists were said to have been beaten and had their equipment smashed, while others were reportedly detained by the security forces.
US state department spokesman Robert Gibbs said the "systematic targeting" of journalists was unacceptable.
Pro-Mubarak groups also prevented food and water from being delivered to anti-government protesters camped out in a square in central Cairo.
Egypt's Health Minister Ahmed Samih Farid said that eight people had died in the fighting, which began on Wednesday, and 890 were injured, nine of them critically.
Another person was later reported killed in clashes on Abdel Monem Riyad Square, also in central Cairo. Many more were injured.
The BBC's Khaled Ezzelarab in Cairo says the shift in focus from Tahrir Square to Abdel Monem Riyad Square appears to indicate a strategic advance for the anti-Mubarak protesters, who have managed to hold their ground in Tahrir and move the clashes elsewhere.
Mr Shafiq told journalists: "As officials and a state which must protect its sons, I thought it was necessary for me to apologise and to say that this matter will not be repeated."
He promised an investigation to find out whether the demonstration was planned or spontaneous.
The protest was causing damage to the economy, he warned.
"I call on the protesters in these demonstrations to feel that with every passing hour there is destruction. Our work is frozen," he said.
"There is very, very great destruction and we will suffer from it a great deal."
Travel ban
Mr Mubarak has said that he will serve out his current presidential term, which ends in September, but will not run for re-election.
State TV quoted Vice-President Omar Suleiman as saying Gamal Mubarak would also not now run for the job.
Mr Suleiman also called for the release of detained demonstrators "not involved in criminal acts", but he said those responsible for the clashes and the "general deterioration in security" would be held accountable.
He said opposition party the Muslim Brotherhood had been invited to talks.
"They're still hesitant to enter dialogue but I believe it's in their interests," he told state TV.
The party has previously rejected government calls for negotiations, saying Mr Mubarak must leave office first.
And in a separate development, the public prosecutor issued a travel ban on three former ministers and a senior member of the ruling party, among them the unpopular former Interior Minister Habib al-Adly.
Correspondents say these legal measures against some of the most powerful people in the country are confirmation of a deep split within the ruling elite.
His statement said other officials were covered by the ban, which would last "until national security is restored and the authorities and monitoring bodies have undergone their investigations".
Unrest has left about 300 people dead across the country over the past 10 days, according to UN estimates.
The BBC's Jon Leyne in Cairo cites a retired general who has been speaking to tank crews on the square as saying the army is losing patience, and if firing continues from pro-government supporters, it is willing to fire on them.
Those attacking them appear to be either police who have taken off their uniforms or plain-clothes "thugs", our correspondent says.
The military leadership seems deeply uncomfortable with what is happening, adds our correspondent; they do not want to turn on protesters but they are not willing to defy the president either.
Meanwhile mobile phone firm Vodafone said the authorities had used its network to send pro-government messages.
If Mr Mubarak does not step down, demonstrators have planned to march on the presidential palace on Friday.
