At least 29 people were killed during anti-government marches on Saturday while thousands rallied in support of the army-led authorities, underlining Egypt's volatile political fissures three years after the fall of autocrat president Hosni Mubarak.
Security forces lobbed teargas and fired in the air to try to prevent demonstrators opposed to the government from reaching Tahrir Square, the symbolic heart of the 2011 uprising that toppled the former air force commander.
Instead of commemorating Mubarak's overthrow, a large number of Egyptians gathered in Tahrir to pledge their support for the army chief who ousted the country's first freely-elected president last year.
The chanting for General Abdel Fatah
al-Sisi underscored the prevailing desire for a decisive military man they count on to end the political turmoil that has gripped Egypt
since the 2011 Arab Spring revolution and crippled the economy.
But an end to street violence seemed nowhere in sight with the sound of tear gas canisters being fired echoing through downtown Cairo as police confronted anti-government protesters.
Four protesters were killed in different parts of the capital, where armored personnel carriers were deployed to try and keep order, and anyone entering Tahrir had to pass through a metal detector.
Egypt marks three years since Morsi ouster (Photo: AFP)
In the southern town of Minya, two people were killed in clashes between Morsi supporters and security forces, said Brigadier General Hisham Nasr, director of criminal investigations in the regional police department.
A woman was killed in Egypt's second city of Alexandria during clashes between supporters of Morsi and security forces.
Al-Sisi toppled President Mohamed Morsi of the Muslim Brotherhood in July after mass protests against what critics called his mismanagement and increasingly arbitrary rule, triggering a confrontation with the veteran Islamist movement that has hit investment and tourism hard.
The general, who served as head of military intelligence under Mubarak, is expected to announce his candidacy for the presidency soon and likely to win by a landslide in elections, expected within six months.
Several leading politicians have indicated they would not run for president if al-Sisi does, highlighting his dominance and the barren political landscape that has emerged since Mubarak's fall. The most vocal critics of the new order - the Brotherhood - have been driven underground.
The army congratulated Egyptians on the anniversary of the 2011 uprising and said it would help people build on the gains of what it calls the June 30 Revolution, a reference to the street unrest that prompted the army to oust Morsi.
Tensions have been smoldering anew since a wave of deadly bombings killed six people in Cairo on Friday. An al Qaeda-inspired group, based in the lawless Sinai Peninsula, claimed responsibility, according to the SITE monitoring organization.
Early on Saturday a bomb exploded near a Cairo police academy. No one was hurt, said the Interior Ministry.
In Tahrir, the mood on Saturday felt more like a campaign rally for al-Sisi than a commemoration of the 18-day revolt that Egyptians at the time hoped would bring democratic, civilian government to the Arab world's most populous country.
Huge banners, posters and T-shirts displayed images of al-Sisi in his trademark dark sunglasses at Saturday's rally. Several hundred people chanted slogans in support of the general.
A woman named Heba dismissed the 2011 uprising and said the important revolution came when Egyptians held mass protests that led to the army takeover last July. "I'm here to support al-Sisi," she said.
Tear gas and birdshot
Others didn't have the chance to express their views. Police fired live rounds in the air to disperse about 1,000 anti-government protesters in Cairo's Mohandiseen district and at two other marches in downtown.
Some of the demonstrators were supporters of the Brotherhood, while others were liberal activists. Witnesses said police also fired tear gas and birdshot at a crowd of activists moving toward Tahrir for an anti-government rally.
Hisham Sadiq, a university student, said he was protesting against "military rule and the thugs of the Interior Ministry".
At one rally, the crowd yelled "the people want the downfall of the regime!" - a common chant during the 18-day revolt that ousted Mubarak - before running from tear gas.
Dozens of anti-government protesters were arrested in Egypt's second city Alexandria, security sources said.
When he removed Morsi, al-Sisi promised a political roadmap that would lead to free and fair elections.
But the Muslim Brotherhood says al-Sisi and his allies in the government have blood on their hands and accuse them of undermining democratic gains made since Mubarak's downfall.
Security forces have killed up to 1,000 Muslim Brotherhood supporters and put the movement's top leaders in jail. The Brotherhood, which renounced violence in the 1970s, has been declared a terrorist group.
But the tough measures have failed to stabilize Egypt, which is of great strategic importance because of its peace treaty with Israel
and control over the Suez Canal.
Islamist militants based in the Sinai Peninsula have stepped up attacks against security forces since al-Sisi toppled Morsi. Hundreds have been killed.
The security crackdown has been extended to secular-minded liberals, including ones who played a key role in the 2011 uprising. Human rights groups have accused the Egyptian authorities of quashing dissent and using excessive force, calling state violence since al-Morsi's ouster unprecedented.
Still, many Egyptians choose to look the other way and extend their full support to al-Sisi. "We are here to support al-Sisi," said a man in Tahrir who only gave his first name, Mahmoud. "Al-Sisi is going to save the country," said his wife.