CAIRO -- In large, state-backed rallies complete with dancing horses and traditional music, military supporters celebrated the anniversary of Egypt's 2011 uprising Saturday, calling for the army chief to run for president. At the same time, security forces cracked down on rival demonstrations by Islamist supporters of the ousted president -- and by secular activists critical of both camps.
The starkly contrasting scenes reflected the three years of turmoil that have split Egyptians into polarized camps since the revolt that began on Jan. 25, 2011, ousting autocratic leader Hosni Mubarak -- followed by last summer's millions-strong demonstrations against Mubarak's elected successor, Islamist Mohammed Morsi, that led to the coup removing him
Morsi's supporters were using Saturday's anniversary for building up a new momentum in defiance to the military and its political transition plan, despite months of a fierce crackdown that has crippled their ranks and rising public resentment against the group. At least four protesters were killed Saturday as security forces cracked down on the marches in Cairo and other cities.
In a defiant statement amid the clashes, the Brotherhood vowed not to leave the streets "until it fully regains its rights and breaks the coup and puts the killers on trial."
Thousands of pro-military demonstrators, meanwhile, turned out in Cairo's Tahrir Square and other sites in rallies to show their support for army chief Gen. Abdel-Fattah el-Sissi, the man who ousted Morsi and whom many of those in the rallies want to now run for president.
Their rallies showed a ferociously anti-Islamist tone-- with chants for "the execution of the Brotherhood" -- translating into fury at anyone believed to be critical of the post-coup leadership. In Tahrir, a crowd was seen beating and shoving a woman in a conservative headscarf, believing she was a Brotherhood sympathizer, as she screamed that she was just trying to get to her home nearby.
They also turned on journalists. More than a dozen journalists were beaten by the demonstrators, or detained by police for protection from angry crowds. Demonstrators chased one Egyptian female journalist, mistakenly believing her to work for Al-Jazeera TV -- seen as pro-Brotherhood. They pulled her hair and tried to strangle her with a scarf until police took her into a building for protection.
Security forces also moved to shut down rallies marking the anniversary by secular youth activists who led the 2011 anti-Mubarak uprising and who are critical of both the Islamists and the military. A number of their most prominent figures have been in prison for months amid a campaign to silence even secular voices of dissent.
One prominent activist, Nazli Hussein, was detained by police on the subway as she headed from her home to join one such rally downtown, her mother, Ghada Shahbendar said. Hussein's lawyer, Amr Imam, said that when he went to see her at the police station, a police shoved him, pointed his rifle at him and warned him he had 10 seconds to leave or he'd shoot.
Police used tear gas to disperse one small gathering by secular activists in the Cairo district of Mohandessin, beating and kicking at least one of them, several participants said.
"The only thing allowed is el-Sissi revolutionaries," one of the activists, blogger Wael Khalil, said with an ironic laugh. "This was supposed to be day to mark the revolution ... I don't get it. Do they think that there will be working democracy this way?"
The days' rallies are taking place in an atmosphere of fear, a day after four bombs exploded in Cairo targeting police and killing six people, believed to be an escalation of a campaign of attacks by Islamic militants. Another 15 people were killed around the country Friday when Morsi's supporters armed with gasoline bombs and firearms loaded with birdshot clashed with security forces. The Interior Ministry said that 237 people were arrested during the protests.
In the northern Sinai Peninsula, where the military has been battling militants for months, an army helicopter crashed Saturday and its crew was missing, a military spokesman said. There was no immediate word on the cause or whether it had been shot down.
Islamists held protests in several neighborhoods of Cairo and in other cities, quickly turning into clashes with security forces. Protesters burned pictures of el-Sissi. Riot police fired tear gas and shot into the air, chasing protesters down side streets in Cairo.
Two protesters were killed in the southern city of Minya and two others in the greater Cairo area in police clashes, security officials said.
In its statement, the Brotherhood appealed to secular youth groups to unite with it in protests
"Continue in your revolt, free and creative revolutionaries ... and keep the ember of your revolution alive, unite on the goals of the revolution," it said. "Pay no mind to the empty threats of the coupists, and their attempt to divide you."
Secular youth groups, however, have shunned the Islamists, who they equally accuse of undermining the 2011 uprising's democracy goals while in power.
The pro-military rallies appeared carefully designed, with marches of demonstrators converging on several locations, particularly Cairo's central Tahrir Square -- the symbolic heart of the 2011 uprising -- and outside the presidential palace in Cairo's Heliopolis district.
The marchers waved Egyptian flags and touted posters, banners and badges with pictures of el-Sissi. A folklore band with dancers in colorful swirling skirts sang and danced their way across bridges over the Nile River into Tahrir, where a dancing horse performed.
"Come down (nominate yourself), oh Sissi," a crowd in Tahrir chanted. Soldiers manning armored personnel carriers at the square's entrances joined demonstrators in chanting, "The people want the execution of the Brotherhood." A military Chinook helicopter circled over Tahrir to cheers from the crowd. Huge loudspeakers blared pro-military songs in the streets.
The al-Qaida-inspired group Ansar Beit al-Maqdis, or the Champions of Jerusalem, claimed responsibility for Friday's bombings, warned of more and told citizens to stay away from police stations.
"We tell our dear nation that these attacks were only the first drops of rain, so wait for what is coming," read the statement, posted on militant websites.
The group, based in Sinai peninsula, claimed responsibility for one of the worst bombings that hit Egypt over the past months, including the assassination attempt of the Interior Minister in September and suicide bombing in Nile Delta city in Mansoura killing 16 mostly policemen. The group says it is avenging the killings of pro-Morsi supporters and military offensive in Sinai.
Early Saturday, a bomb exploded next to a police training institute in eastern Cairo, said Hani Abdel-Latif, a spokesman for Egypt's Interior Ministry. He said it only damaged the facility's walls and caused no casualties.
Ahmed Mahmoud, an engineering student living close by, angry residents quickly blamed the Brotherhood.
"People were saying they will carry arms and kill all Muslim Brothers who dare to pass by this place," he said.