Originally published February 3, 2011 at 9:13 a.m., updated February 3, 2011 at 10:41 a.m.
The Egyptian army stepped in Thursday to separate pro-government rioters from those seeking to hasten President Hosni Mubarak's exit after a night of clashes that killed at least six people and wounded hundreds.
Troops fanned out to form a buffer zone between the two sides in Tahrir Square in central Cairo but then stepped aside hours later as anti-government protesters surged forward to resume fighting with Mubarak supporters.
With volleys of stones, the opposition protesters pushed back their rivals and swarmed onto a nearby highway overpass that pro-Mubarak fighters had used the day before as high ground to rain down paving stones and firebombs.
Protesters had shielded themselves with metal sheets pulled from nearby shops as the sky was lit by streaks of fire from Molotov cocktails during a 15-hour spasm of violence that began Wednesday.
"We saw running street battles all through the night ... around Tahrir Square," NPR's Lourdes Garcia-Navarro reported. "There was some gunfire overnight, but it's not clear who was shot at and who fired. It's a very chaotic scene."
Military helicopters circled overhead Thursday morning as protesters tired and battered by the night of street fighting appeared to rally, renewing anti-Mubarak chants and vowing not the leave the square until their president is removed from power.
Vice President Omar Suleiman promised that Mubarak's son, Gamal, will not seek to succeed his father in presidential elections in September, according to reports on state TV. Many Egyptians adamantly oppose the prospect of another Mubarak in high office.
In another move to ease the unrest, Prime Minister Ahmed Shafiq took the unprecedented step of apologizing for the Tahrir Square violence by pro-Mubarak supporters, some of whom charged through the square cavalry-style on horses and camels.
Shafiq told state TV that the attack Wednesday was a "million percent wrong" and promised to investigate who was behind it. Protesters have accused the regime of organizing the assault, using paid thugs and policemen in civilian clothes hired by the ruling National Democratic Party in an attempt to crush their anti-government movement.
The notion that the state may have coordinated violence against protesters, whose vigil in Tahrir Square had been peaceful for days, prompted a sharp rebuke from Washington, which has considered Egypt its most important Arab ally and sends it $1.5 billion a year in aid.
"If any of the violence is instigated by the government, it should stop immediately," White House Press Secretary Robert Gibbs said.
At a National Prayer Breakfast on Thursday, President Obama called for prayers "that a better day will come to Egypt."
A spokesman for the protest movement Kefava, one of myriad anti-Mubarak factions, told Al-Jazeera television that the blatant attack on peaceful demonstrators meant no negotiations were possible with the regime and that it "made us more determined to remove President Mubarak."
Egypt's Health Ministry said six people were killed overnight and 836 wounded.
Although the army mostly refused to intervene in Wednesday's fighting, it finally took its first muscular action after a barrage of deadly automatic weapons fire against the protesters before dawn Thursday, killing at least three protesters in Tahrir Square.
Soldiers lined up in between the two sides around 11 a.m. local time, and four tanks cleared the highway overpass from which Mubarak supporters had hurled rocks and firebombs onto the protesters.
But even as the army appeared to be cracking down on violence, more pro-government demonstrators were arriving. "Hundreds of men" were lined up at one checkpoint manned by Mubarak supporters as they waited to get into the square, NPR's Corey Flintoff reported.
"They seem to be showing some sort of I.D. and they're going through. I've seen some men carrying cardboard boxes and bags," Flintoff said. "It's impossible to tell what they're carrying, whether it's food or weapons of some sort. But there seems to be [a] fairly well-organized effort to fill the street that leads to the square with pro-Mubarak demonstrators."
A sense of victory ran through the protesters Thursday even as they organized their ranks in the streets in case of a new assault. "Thank God, we managed to protect the whole area," said Abdul-Rahman, a taxi driver who spent the night in the square. "We prevented the pro-Mubarak people from storming the streets leading to the square." He refused to give his full name.
The anti-Mubarak movement, which has carried out an unprecedented 10 days of protests bringing as many as a quarter-million people into Tahrir Square, has vowed to intensify protests to force him out by Friday. In a speech Tuesday night, Mubarak refused to step down immediately, saying he would serve out the remaining seven months of his term — a concession rejected by the protesters.
The unrest has bred deep suspicion among many people in Cairo, the vast majority of whom stayed clear of the melee taking place in Tahrir.
When NPR and other news agencies tried going into one middle-class neighborhood outside the battle zone to see how people were coping with the chaos, "we were mobbed, beaten and accused of being spies," Garcia-Navarro said.
The Egyptian army held the journalists and others for some time, apparently for their own protection.
Medhat Saad, an Egyptologist and tour operator who spoke to NPR by phone from his home in Cairo, said the prisons have been emptied and criminals were running the streets.
"We are just guarding the whole neighborhood," he said, adding that he had no idea how or why the inmates had been released.
Saad, who participated in the first days of the anti-Mubarak protests, said he gave up when police attacked and killed "maybe 200" protesters. Now he and his family are holed up in their home waiting for Mubarak to quit and the violence to end. But he is not optimistic.
"I started thinking seriously to leave the country, actually," he told NPR. "It's a hopeless case. What happens if this man stays in power — it will be a disaster for Egypt."
NPR's Lourdes Garcia-Navarro and Corey Flintoff reported from Cairo for this story, which contains material from The Associated Press.