New looting and arson spread around the capital.
Gangs of thugs supporting President Hosni Mubarak attacked reporters, foreigners, and human rights workers and the army rounded up foreign journalists.
Gunfire rang out in central Tahrir Square, where Mubarak supporters and opponents have been fighting for more than 24 hours.
At least one wounded person was carried out. At least eight people have been killed since the clashes erupted Wednesday afternoon.
Security officials said a fire is raging in a major supermarket outside Sheikh Zayed, a suburb of the capital, and looters were ransacking the building. Another building much closer to the square and next to a five-star hotel tower overlooking the Nile River was also on fire.
The officials said other fires have erupted in the Cairo district of Shubra, north of the centre.
The violence came despite attempts by the Army to separate the two sides.
Earlier Egypt’s prime minister apologised for an attack by government supporters on protesters in a surprising show of contrition.
The government offered more concessions to try to calm the wave of demonstrations demanding the removal of President Hosni Mubarak.
Vice President Omar Suleiman promised that Mubarak’s son, Gamal, will not seek to succeed his father in presidential elections in September, state TV said.
Also, the prosecutor-general banned travel and froze the bank accounts for the former interior minister whose police led a bloody crackdown against the protesters last week and against two other former ministers who were among the unpopular millionaire businessmen wielding heavy influence in the previous government.
The steps came after the protesters who have camped out for days in central Tahrir Square fended off the assault launched on Wednesday by regime supporters.
The uncontrolled violence raged through the night, killing eight people as the two sides battled with rocks, sticks, bottles and firebombs and soldiers largely stood by without intervening.
The military finally took its first muscular action after a barrage of deadly automatic weapons fire against the protesters before dawn today.
Soldiers pushed back the pro-government attackers and took up positions between the two sides.
Then in the afternoon, the soldiers largely stepped aside as the anti-government side surged ahead in resumed clashes.
With volleys of stones, the protesters pushed back their rivals swarmed onto a nearby highway overpass that the regime supporters had used as a high ground to batter them.
At the same time, Mubarak supporters carried out a string of attacks on journalists around the square. The US State Department condemned the attacks, calling them a “concerted campaign to intimidate” the media – the latest in mounting criticism by Mubarak’s top ally.
One Greek print journalist was stabbed in the leg with a screwdriver, and a photographer was punched, his equipment smashed. Arab TV network Al-Jazeera reported two correspondents attacked. The army started rounding up journalists, possibly for their own protection.
The protesters accuse the regime of using paid thugs and policemen in civilian clothes in an attempt to crush their movement.
The Interior Ministry denied any of its police were involved
Prime Minister Ahmed Shafiq acknowledged that the attack “seemed to have been organised” and said elements had infiltrated what began as a demonstration against the protesters to turn it violent.
But he said he didn’t not know who, promising an investigation into who was behind it.
“I offer my apology for everything that happened yesterday because it’s neither logical nor rational,” Shafiq told state TV. “Everything that happened yesterday will be investigated so everyone knows who was behind it.”
Shafiq, a former air force general appointed by Mubarak over the weekend, said he was willing to go to Tahrir to meet protesters but urged them to disperse.
At a press conference aired on state TV, Shafiq defended Mubarak’s announcement this week that he would serve out the remaining seven months of his term. “Would it be dignified for a nation for its president to leave immediately? .. There are ethics that must be observed.”
The notion that the state may have co-ordinated violence against protesters, whose vigil in Tahrir Square had been peaceful for days, raised international outrage.
It brought a sharp rebuke from Washington, which sends Egypt $1.5bn (€1bn) a year in aid.
“If any of the violence is instigated by the government, it should stop immediately,” said White House Press Secretary Robert Gibbs.
The anti-Mubarak movement has vowed to intensify protests to force the president out by Friday. In a speech on Tuesday night, Mubarak refused to step down immediately, saying he would serve out the remaining seven months of his term – a halfway concession rejected by the protesters.
Today, a sense of victory ran through the protesters, even as they organised their ranks in the streets in case of a renewed assault.
“Thank God, we managed to protect the whole area,” said Abdul-Rahman, a taxi driver who was among thousands who stayed hunkered in the square through the night, hunkered down against the thousands besieging the entrances. “We prevented the pro-Mubarak people from storming the streets leading to the square.” He refused to give his full name.
Bands of Mubarak supporters moved through side streets, trading volleys of stone-throwing with the protesters and attacking cars to stop supplies from reaching the protest camp.
The Mubarak backers seethed with anger at a protest movement that state TV and media have depicted as causing the chaos and paralysing businesses and livelihoods. “You in Tahrir are the reason we can’t live a normal life,” one screamed as he threw stones in a side street.
The anti-Mubarak youths posted sentries on the roofs and balconies of buildings around the square to raise the alert of any approaching attackers and rain stones on them. Other look-outs in the streets banged metal poles against pedestrian barriers in an alarm when they sighted incoming Mubarak backers.
The men who led the defence and throughout the night were easily identified. Many had cotton padding and grubby bandages dangling from their faces, arms and legs. Many had chunks of rock stuck to their hair and clumps of dust in their beards. A large number had the trimmed beards of Muslim conservatives, a sign of how the Muslim Brotherhood had a major role in the fight.
Wednesday’s assault began in the afternoon, when thousands of pro-Mubarak attackers broke into the square where some 10,000 protesters were gathered.
The two sides traded volleys of rocks and Molotov cocktails for much of the night.
The escalation came around 4 am when sustained bursts of automatic gunfire and single shots rattled the darkness for more than two hours.
Soon after, the military moved. Four tanks cleared a highway overpass from which Mubarak supporters had hurled rocks and firebombs onto the protesters.
On the streets below, several hundred soldiers carrying rifles lined up between the two sides, pushing the pro-government fighters back and blocking the main battle lines in front of the famed Egyptian Museum and at other entrances to the square.