At least two protesters were killed and nearly a thousand more wounded as clashes erupted in three of the country's biggest cities in scenes redolent of the uprising that overthrew Hosni Mubarak, the former president, nine months ago.
For the first time since the revolt, Egypt's black-uniformed police force, one of Mr Mubarak's most hated instruments of repression, was deployed in force.
For two days they battled an ever swelling number of protesters in central Cairo, opening fire with tear gas, rubber bullets and bird shot in the city's Tahrir Square – the epicentre of the revolution that toppled Mr Mubarak – and the streets and alleyways off it.
The demonstrators retaliated with an endless volley of stones and the occasional Molotov cocktail and by Sunday afternoon the storied square appeared once again to be in the hands of the people. Just as in late January and early February, protesters erected barricades at its entrance points, checking the identity papers of all who wanted to gain access.
The protests were far smaller than at the height of the revolution, with fewer than 10,000 in the square, but the ferocity of the violence and the speed with which it spread to Alexandria and Suez, cities at the forefront of the revolution, pointed to the dangerously volatile situation in which Egypt once again finds itself.
Egypt's transition to civilian rule, which passes a major milestone when the first elections since Mr Mubarak's downfall are held next week, has been far from smooth.
But never before has the antipathy towards the military leadership that has managed Egypt since February been as marked as it is now. Hailed as the people's saviours during the revolution, the army is now perceived as the principal obstacle to Egypt achieving democracy. Under the leadership of Field Marshal Hussein Tantawi, the Supreme Council of the Armed Forces has been accused of drawing out the transition and plotting to ensure that the army remains the supreme arbiter in the land.
Protesters in Tahrir Square insisted they would not leave until the army surrendered power, saying they now saw no difference between the generals and the president they succeeded.
"We have a single demand: The marshal must step down and be replaced by a civilian council," Ahmed Hani, one protester, was quoted as saying. "The violence yesterday showed us that Mubarak is still in power."
Freshly scrawled graffiti near the square put it more succinctly: "The marshal is Mubarak's dog."
Many Egyptians will blame the intensity of the violence on police overreaction. The clashes were sparked when police forcibly attempted to dismantle a tented camp in Tahrir Square manned by fewer than 200 protesters who had gathered to mourn relatives killed in the uprising against Mr Mubarak.
With news spreading of police beatings, thousands more converged on the square, which was quickly engulfed in chaos. As the clashes intensified, protesters set alight an armoured military vehicle and two police cars.
The mood soured further as protesters discovered that the police, just as they had done in January and February, were using tear gas canisters with US and Hebrew markings.
Hopes that the violence can be reined in may depend on how the army and the civilian cabinet it appointed responds. So far, however, the response has been unyielding.
Mansour el-Essawy, the interior minister whose resignation was demanded by the protesters, insisted that the police had nothing to do with the violence, claiming, in a throwback to the language of the Mubarak era, that the demonstrators had shot at each other.
It was a claim that was challenged by protesters, witnesses and journalists, two of whom were reportedly shot in the face by a police officer standing on top of an armoured vehicle. A number of protesters were partially blinded, among them Malek Mostafa, a prominent activist who was said to have lost his right eye.
Orignal From: Thousands of protesters seal of Egypts Tahrir Square