A deadly mob attack on Shi'ite villagers near Cairo has exposed yet another fault line in an increasingly divided Egypt. The killings also reflect the increasingly violent turn toward sectarianism across the Arab world.
Representing just one percent of Egypt's population, Shi'ite Muslims would seem an unlikely threat to the country's overwhelming Sunni majority.
But on Sunday a crowd of angry Sunnis, including followers of the ultraconservative Salafi sect, attacked a group of Shi'ites on the outskirts of the capital, killing four of them.
Security forces say the mob accused the men of trying to spread their Shi'ite religious views.
While Christians and Baha'is say they face more discrimination under Egypt's Islamist-led government, Shi'ite Muslims also are increasingly a target.
Political sociologist Said Sadek of the American University in Cairo noted that Egypt's new basic law places Shi'ites at a disadvantage.
"Their rights are very little. For the first time in Egyptian history, the Egyptian constitution is sectarian. It is only focusing on Sunni. It does not talk about Shia," said Sadek.
Anti-Shi'ite sentiment grew earlier this year, when President Mohammed Morsi played host to Iran's Shi'ite leaders, prompting Salafist protests.
It became more vehement in recent weeks, with a prominent Egyptian Sunni cleric calling on Sunnis to undertake jihad in Syria.
The Syrian conflict has unleashed a wave of sectarianism across the region, as the peaceful political protests against President Bashar al Assad, of the minority Allawite sect - an offshoot of Shi'ism - descended into religious divides both at home and abroad.
Sunni Gulf states have been major backers of the opposition, while Iran and the Lebanese militant group Hezbollah support Assad.
Political analyst Hala Mustafa said, "I think Middle East is going toward now a sectarian split between the Shi'ite camp and the Sunni one.”
Mustafa, former editor of Democracy Journal, also noted that the recent sectarianism in Egypt also has a local angle: a call for Sunni unity at a time of increasing polarization within the country.
Morsi, who hails from the Muslim Brotherhood, increasingly has sought support from rival Salafis ahead of mass anti-government protests planned for June 30.
With a showdown between Islamists and their secular and nationalist opponents brewing, the head of Egypt's military said it may step in should the situation spiral out of control.
Defense Minister Abdel Fattah al-Sisi said Sunday “the will of the Egyptian people alone is what governs us" and the military will protect it. It was not immediately clear to whose will he was referring - those who chose Morsi as Egypt's first democratically elected president - or those who would have him step down.
For decades the armed forces were the guarantor of secular stability in Egypt, and General al-Sisi warned Sunday against sectarian strife. Under the new government, however, the military retreated from its interim period on the political stage to a Morsi-backed, constitutionally protected position on the sidelines.
Political analyst Mustafa said that any army intervention likely will have only one thing in mind, and it is not the original goal of the revolution.
"This of course won't be in the favor of democracy. It will be in the favor of stability,” said Mustafa.
And in Egypt, she noted, those are two very different issues. But with sectarianism on the rise, and political discontent threatening to boil over, some Egyptians say that is not the worst possible outcome.