It has come to be known as the "Battle of the Mountain": a ferocious fight between members of Egypt's Muslim Brotherhood and their opponents near the group's Cairo headquarters. In a country that has already seen crisis after crisis, it could mark a dangerous turning point in the political turmoil.

The aftermath of the fighting is raising worries that the confrontation between Islamists who dominate power in the country and their opponents is moving out of anyone's control.

The riot revealed a new readiness of some in the anti-Brotherhood opposition to turn to violence, insisting they have no choice but to fight back against a group they accuse of using violence against them for months. The fight saw an unusual vengefulness. Young protesters were seen at one point pelting a Brotherhood member with firebombs and setting him aflame. Others chased anyone with a conservative Muslim beard, while Islamists set up checkpoints searching for protesters. Each side dragged opponents into mosques and beat them.

Since the fight, Islamists enraged by what they saw as an aggression against their headquarters have for the past week hiked up calls for wider action against opponents — and the media in particular — accusing them of trying to overthrow Islamist President Mohammed Morsi.

Those calls may explain moves by the country's top prosecutor the past week: the questioning of a popular television comedian, Bassem Youssef, whose Jon Stewart-style satires of Morsi drive Islamists into knots of anger, the summoning of several other media personalities and the issuing of arrest warrants against five opposition activists on accusations of fomenting violence.

Opposition activists warn the moves are the opening of a campaign of intimidation to silence Morsi's critics. The presidency says the prosecutor is just enforcing the law and that Morsi's office has nothing to do with the moves. Morsi's supporters say they are showing restraint against extreme provocation.

But rhetoric within the Brotherhood has increased in fervor. This week, Brotherhood head Mohammed Badie accused "some politicians" of "trying to "generate something like a civil war in the community," in an apparent reference to opposition leaders.

"After all that blood and all the criminality in the street, there must be decisiveness," Gamal Heshmat, a lawmaker with the Brotherhood's political party, said of the recent arrest warrants. "This is a public demand. Now people must prove their innocence."

For opponents of Morsi, the battle was a sign that anger at the Brotherhood is spreading beyond their circles to the broader public, nine months into the administration of Brotherhood veteran Morsi.

Ziad el-Oleimi, a former lawmaker and revolutionary activist who lives in the neighborhood where the clashes took place, said local residents were behind the worst beatings of Brotherhood members, rather than the protesters who led the day's march on the group's headquarters.

Previous Brotherhood aggression "is starting to provoke people," said el-Oleimi, who was a leading figure in the 2011 protests that toppled Morsi's predecessor Hosni Mubarak. "This time was a game changer. They had anticipated they would beat up the protesters, the opposition and teach them a lesson. This is not what happened." Locals had already filed reports to local authorities demanding that the Brotherhood office be removed from their neighborhood.

The fury growing for months was on display in the March 22 clashes in Moqattam, a district located on a rocky plateau overlooking Cairo where the Brotherhood's headquarters is located.

Both sides came ready for a fight. Opponents had called for a march on the Brotherhood headquarters to "restore dignity" after an incident a week earlier when Brotherhood members beat up activists who were spray-painting graffiti outside the building, as well as journalists filming the incident, slapping one woman to the ground.

The Brotherhood brought in several thousand supporters, vowing to defend the building, referring to it as "our home."

The mayhem erupted the minute the two sides faced off, and each accuses the other of throwing the first stone. The heaviest fighting was in a roundabout several kilometers away from the Brotherhood headquarters, which was guarded by lines of police. Rains of stones and gunshots were exchanged, while so-called "popular committees" formed by residents to protect their neighborhood joined in, swinging poles and machetes.

All day and into the night, the two sides battered each other with everything from knives and iron bars to homemade pistols, leaving 200 injured.

Bearded Brotherhood members dragged dozens of activists into the Bilal bin Ramah Mosque, where they beat them and flogged them with whips, several of those who were held told The Associated Press.

Christian activist Amir Ayad recalled how, while he was being beaten, he'd hear Brotherhood supporters coming into the mosque greeted by their comrades who told them, "Go warm up on that Christian dog inside." Ayad — who was left with a broken skull and ribs — said Brotherhood members forced him to pose for photograph, wielding a knife they pushed into his hands to use as evidence that he was thug.

Opponents, meanwhile, snatched a number of Brotherhood members into the Al-Hamad Mosque. A reporter for the Brotherhood's party newspaper, Mustafa el-Khatib, told AP he was seized and carried by his arms and legs into the mosque and beaten.

"You sheep, we'll show you," his tormentors shouted, using a term many protesters use against Islamists they see as blindly following their leaders, el-Khatib told The AP. He had deep cuts to the head and bruises all over his body.

Many in the anti-Morsi camp said they were bringing their protests to the real power in the country — the Brotherhood. The 85-year-old fundamentalist group forms the backbone of Morsi's leadership, though the presidency and the group both deny the Brotherhood has any role in his decisions.

"We came to say that Morsi is not a president. It is Badie and (Khairat) el-Shater," said Fatma Khalifa, a 30-year-old protester, referring to the Brotherhood's top two figures. "Morsi is just an envoy."

They were also fired with anger over previous Islamist violence against them. In December, Morsi backers attacked a sit-in protest outside the presidential palace in Cairo, leading to hours of clashes between the two sides that left 10 dead. During that fighting, Islamists set up an impromptu detention center, seizing and beating protesters.

Morsi supporters have attacked other, smaller protests, including one in October when they stormed a stage set up by protesters in Tahrir Square, smashing loudspeakers because of slogans they saw as insulting the president. The result again was clashes that left 100 injured. January and February saw heavy fighting between police and protesters around the country that killed dozens, and opponents blame Morsi, saying he pushed police to put down the protests.

Brotherhood members, in turn, point to arson attacks on several of their party offices around the country over the past months and say waves of protests have undermined their governing of the nation. They have progressively become more direct in blaming opposition politicians — moving from urging them to denounce the violence to accusing some of using unrest to topple the elected president.

In a finger-wagging speech after the Moqattam battle, Morsi warned opponents he would take measures to "protect this nation." He also accused the media of inciting violence, and the Brotherhood echoed that with a statement accusing "hostile" media of "fabricating lies against" the group.

Mourad Ali, a media adviser for the Brotherhood's Freedom and Justice Party, acknowledged the rising anger among Morsi's supporters. "I know young Islamists are charged up, and anger at the crimes in Moqattam has reached the top," he wrote on his Facebook page. He called for the "revenge (to) be legal and creative," urging members to collect evidence against those behind the violence.

Among Morsi opponents, there is a fear of a campaign against them, but also a sense that they showed they can fight back.

Wael Abdel-Fattah, a cultural columnist at Al-Tahrir newspaper and a sharp critic of the Islamists, said Moqattam shattered the myth of an "invincible" Brotherhood and showed no one has a monopoly on force.

"The violence started when the means for political protesting were shut," he said. He spoke of "a new kind of balance in violence," adding, "This balance can either create a new political awareness or push toward more violence where everyone knows they will pay the price."