Hundreds were wounded and three people were killed on Wednesday as several thousand supporters of President Hosni Mubarak attacked anti-government protesters in Cairo by raining stones, bottles and firebombs on each other in scenes of uncontrolled violence as soldiers stood by without intervening.

Government backers galloped in on horses and camels, only to be dragged to the ground and beaten bloody.

At one of the fighting's front lines, next to the famed Egyptian Museum at the edge of Tahrir Square, pro-government rioters blanketed the rooftops of nearby buildings and dumped bricks and firebombs onto the crowd below — in the process setting a tree ablaze inside the museum grounds. Plainclothes police at the building entrances prevented anti-Mubarak protesters from storming up to stop them.

The two sides pummeled each other with hurled chunks of concrete and bottles at each of the six entrances to the sprawling plaza, where the 10,000 anti-Mubarak protesters tried to fend off the more than 3,000 attackers who besieged the square. Some on the pro-government side waved machetes, while the square's defenders filled the air with a ringing battlefield din by banging metal fences with sticks.

The protesters accused Mubarak's regime of unleashing a force of paid thugs and plainclothes police to crush their unprecedented 9-day-old movement demanding his ouster, a day after the 82-year-old president refused to step down. They showed off police ID badges they said were wrested off their attackers.

"After our revolution, they want to send people here to ruin it for us," said Ahmed Abdullah, a 47-year-old lawyer in the square. "Why do they want us to be at each other's throats, with the whole world watching us."

Another man shrieked through a loudspeaker, "Hosni has opened the door for these thugs to attack us."

Amid the mayhem, the anti-Mubarak camp turned the interior of the square into a support base: Dozens of men and women pried up the sidewalk with bars, broke it into pieces and ferried the piles of ammunition in canvas sheets to their colleagues at the front. Others directed fighters to streets needing reinforcements. Entrances to a subway station under the square were turned into impromptu prisons, with seized attackers tied up and held at the bottom of the stairs.

The health minister announced one dead — a person in civilian clothes who may have been a policeman fell off a nearby bridge — and nearly 600 injured. Al Arabiya reported that three people were killed by Wednesday evening.

Bloodied young men staggered or were carried into makeshift clinics set up in mosques and alleyways by the anti-government side.

Protesters pleaded for protection from soldiers stationed at the square, who refused. Soldiers did nothing to stop the violence beyond firing an occasional shot in the air and no uniformed police were in sight. Some protesters wept and prayed in the square where only a day before they had held a joyous, peaceful rally of a quarter-million, the largest yet in more than a week of demonstrations demanding Mubarak leave power.

Shots were heard fired in the air in Cairo's Tahrir Square on Wednesday, a Reuters witness said. It was not immediately clear where the shots came from.

An Al-Jazeera correspondent earlier said the army had fired shots in the air, but both state television and Egypt's army deny that any shots had been fired.

The turmoil was the first significant violence between supporters of the two camps in more than a week of anti-government protests. It erupted after Mubarak went on national television the night before and rejected demands he step down immediately and said he would serve out the remaining seven months of his term.

A military spokesman appeared on state TV Wednesday and asked the protesters to disperse so life in Egypt could get back to normal. The announcement could mark a major turn in the attitude of the army, which for the past two days has allowed protests to swell, reaching their largest size yet on Tuesday when a quarter-million peacefully packed into Cairo's central Tahrir Square.

Nearly 10,000 protesters massed again in Tahrir on Wednesday morning, rejecting Mubarak's speech as too little too late and renewing their demands he leave immediately.

In the early afternoon Wednesday, around 3,000 Mubarak supporters break through a human chain of anti-government protesters trying to defend thousands gathered in Tahrir, according to an Associated Press reporter at the scene.

Chaos erupted as they tore down banners denouncing the president. Fistfights broke out as they advanced across the massive square in the heart of the capital. The anti-government protesters grabbed Mubarak posters from the hands of the supporters and ripped them.

From there it escalated into outright street battles. The two sides tore up stones from the street and from a nearby construction site and began hurling stones, chunks of concrete and sticks at each, chasing each other as the protesters' human chains moved back to try to shield the larger mass of demonstrators at the plaza's center.

At one point, a small contingent of pro-Mubarak forces on horseback and camels rushed into the anti-Mubarak crowds, swinging whips and sticks to beat people. Protesters retaliated, dragging some from their mounts, throwing them to the ground and beating their faces bloody. The horses and camels likely were the ones used by touts giving rides for tourists.

Gunfire rang out as some soldiers fired in the air in an attempt to control the crowd. But fighting was unabated. A front-line formed on a street next to the Egyptian Museum — the famed treasury of pharaonic antiquities and mummies — as protesters and government backers, some of whom brandished machetes, hurled projectiles at each other from either side of several abandoned military trucks.

Protesters were seen running with their shirts or faces bloodied. Men and women in the crowd were weeping. Scores of wounded were carried to a makeshift clinic at a mosque near the square and on other side streets. Doctors in white coats rushed about with bags of cotton, mercurochrome and bandages. One man with blood coming out of his eye stumbled into a side-street clinic.

The army troops who have been guarding the square had been keeping the two sides apart earlier in the day, but when the clashes erupted they largely did not intervene. Most took shelter behind or inside the armored vehicles and tanks stationed at the entrances to Tahrir.

Some anti-Mubarak protesters argued with soldiers, begging them to help. "Why don't you protect us?" some shouted, while soldiers replied they did not have orders to do so and told people to go home.

Many protesters — who for days have showered the military with love for its neutral stance — now accused the troops had intentionally allowed the attackers into the square. "Hosni has opened the door for these thugs to attack us," one man with a loudspeaker shouted to the crowds during the fighting.

"These are paid thugs," another protester, 52-year-old Emad Nafa, said of the attackers. "The army is neglectful. They let them in."

The new tensions began to emerge immediately following Mubarak's speech Tuesday night. Later in the night, clashes erupted between pro- and anti-government demonstrators in the Mediterranean city of Alexandria, while in Cairo groups of Mubarak supporters took to the streets, some carrying knives and sticks.

Gatherings of Mubarak supporters have also taken a harsher tone against journalists and foreigners. Two Associated Press correspondents and several other journalists were roughed up during various such gatherings.

State TV reported Tuesday night that foreigners were caught distributing anti-Mubarak leaflets, apparently trying to depict the movement as foreign-fueled.

The violence could represent a dangerous new chapter in the nearly 10 days of upheaval that has shaken Egypt, which has already taken a series of dramatic and unpredictable twists.

After years of tight state control, protesters emboldened by unrest in Tunisia took to the streets on Jan. 25 and mounted a once-unimaginable series of demonstrations across this nation of 80 million. Initially, police cracked down hard with brutal and deadly clashes on the demonstrators.

Then police withdrew completely from the streets for the day, opening a wave of looting, armed robberies and arson — largely separate from the protests themselves — that stunned Egyptians.

But since Sunday, the army moved in to take control and the situation became more peaceful. The military announced it would not stop protests.

As a result, the demonstrations swelled dramatically, protesters gained momentum and enthusiasm and many believed Mubarak's immediate fall was at hand. The United States put intense pressure on Mubarak to bring his rule to an end while ensuring a stable handover.

Wednesday's events could mean the regime has had enough, and that it and the military aim to ensure the end of the unrest after the 82-year-old Mubarak made the concession of announcing he would not run for a new six-year term in September elections.

As if to show the crisis was ending, the government began to reinstate Internet service after days of an unprecedented cutoff, and state TV announced the easing of a nighttime curfew, which now runs from 5 p.m. to 7 a.m. instead of 3 p.m. to 8 a.m.

Mubarak supporters were on the street in significant numbers for the first time on Wednesday. Across the Nile River from the chaos in Tahrir Square, around 20,000 pro-government demonstrators held a rally in front of Mustafa Mahmoud Mosque in the upper-class neighborhood of Mohandiseen.

They waved Egyptian flags, their faces painted with the black-white-and-red national colors, and carried a large printed banner with Mubarak's face as police officers surrounded the area and directed traffic. They cheered as a military helicopter swooped overhead.

Many said they came after seeing a notice on state television to attend the protest. Some appeared to be the sort of young toughs that the opposition accuses the regime of paying to be its fist in the streets.

But the large majority were middle-class families, some of whom said Mubarak's concessions were enough and that they feared continued instability and shortages of food and other supplies if protests continue.

"I want the people in Tahrir Square to understand that Mubarak gave his word that he will give them the country to them through elections, peacefully, now they have no reason for demonstrations," said Ali Mahmoud, 52, who identified himself as middle-class worker from Menoufia, a Nile Delta province north of Cairo.

The movement against Mubarak, meanwhile, was working to prevent any slipping in its ranks after the speech and resist any sentiment that the concession may have been enough.

"We recognize deceit when we see it," said protester Nasser Saad Abdel-Latif. "No one will lose their energy ... We won't go until he goes."

One protest organizer said the regime was going all out to pressure people to stop protesting.

"Starting with the emotional speech of Mubarak, to the closure of banks, the shortage of food and commodities and deployment of thugs to intimidate people, these are all means to put pressure on the people," said Ahmed Abdel-Hamid, a representative of the Revolutionary Committee, one of several youth groups that organized the protests.

The movement is fueled by deep frustration with an autocratic regime blamed for ignoring the needs of the poor and allowing corruption and official abuse to run rampant. Tuesday's massive rally in Tahrir showed a large cross-section of Egyptian society.

In his 10-minute speech Tuesday night, Mubarak hit on one of the themes that has been his evocative for some Egyptians in justifying his rule during his nearly three decades in power — that he can keep stability. Now he was promising to do so as he heads out the door.

The president, who almost never admits to reversing himself under pressure, insisted that even if the protests demanding his ouster had not broken out, he would not have sought a sixth term in September.

Somber but firm — without an air of defeat — he said he would serve out the rest of his term working "to accomplish the necessary steps for the peaceful transfer of power." He said he will carry out amendments to rules on presidential elections.

He vowed he would not flee the country. "This is my dear homeland," he said. "I have lived in it, I fought for it and defended its soil, sovereignty and interests. On its soil I will die. History will judge me and all of us."

The step came after heavy pressure from his top ally, the United States. Soon after Mubarak's address, President Barack Obama said at the White House that he had spoken with Mubarak and "he recognizes that the status quo is not sustainable and a change must take place." Obama said he told Mubarak that an orderly transition must be meaningful and peaceful, must begin now and must include opposition parties.

Earlier, a visiting Obama envoy — former ambassador to Egypt Frank Wisner, who is a friend of the Egyptian president — met with Mubarak and made clear to him that it is the U.S. "view that his tenure as president is coming to a close," according to an administration official, who spoke on condition of anonymity because of the delicacy of the ongoing diplomacy.