CAIRO—Egyptian security forces and plainclothed men clashed with thousands of protestors in downtown Cairo on Friday, killing at least one person and leaving hundreds wounded.

It was the second fatal outburst in Cairo in three days, sharpening a showdown with the country´s ruling generals at a critical stage in Egypt´s messy transition to democratic rule. In less than three weeks, Egyptians will vote in the first stage of a presidential election meant to mark the end of military rule in the country.

Protestors who fought with soldiers are critical of how the country´s ruling generals, who have overseen Egypt since Hosni Mubarak´s February 2011 ouster, are handling the country´s transition. The protesters have focused in particular on the generals´ management of the presidential elections, fearing they are intent on holding on to power, a charge the generals have denied.

The presidential vote is due to begin on May 23, with a runoff set for June 16.

The latest round of violence is troubling for drawing new political forces into the fray. The front lines in Friday´s clashes consisted in part of hardline Islamist Salafis who had long refused to enter into open confrontation with the ruling military. But some Salafis have grown increasingly defiant after their favored presidential candidate, Hazem Abu Ismail, was banned from running on the grounds that his mother has American citizenship.

The latest violence began Wednesday, as Mr. Abu Ismail´s supporters were the primary participants in a sit-in outside a Ministry of Defense compound in downtown Cairo. They were attacked by what protesters said were plainclothed thugs, leaving at least 11 people dead. The military warned Thursday that they wouldn´t tolerate future demonstrations in front of the compound, which houses the ruling military council´s headquarters.

On Friday, as a peaceful demonstration in Cairo´s central Tahrir Square drew to a close, thousands of protestors marched a few blocks away to the military headquarters and pressed up against its barbed- wire barricades.

"The people want to execute the field marshal," some protestors chanted, referring to Field Marshal Mohammed Tantawi, Egypt´s top general. A cleric with a megaphone called on rank-and-file soldiers to abandon their posts and join demonstrators.

"The army has to choose, the military council or the revolution," the cleric shouted. The soldiers appeared not to heed the call.

Amid the group of protestors were those waving the flag of the staunchly secular Revolutionary Socialist movement, and the black-and- white flag favored by militant jihadi groups across the region, including Al Qaeda.

The sight of hardline Islamists battling the military in the streets is likely to be jarring to more secular Egyptians who still remember the violent insurrection that militant Islamist waged against Mr. Mubarak´s government in the 1990s.

Shortly after 3 p.m., the shouting and taunting gave way to violent confrontation. What exactly triggered it remained unclear. Some said soldiers grabbed three protestors out of the crowd. Others said protestors began to break through the barricades, prompting soldiers to react more forcefully. State television broadcast graphic footage of the clashes, suggesting the military has calculated that it has the sympathy of the majority of Egyptians.

Soldiers and protestors began hurling fist-sized rocks at each other, before the military wheeled out water cannons and tear gas to disperse protestors, charging down the street in a phalanx of helmet clad riot police with iron shields, several witnesses said. These people said that as protestors retreated from the advancing phalanx, the plainclothed men joined the fray, attacking protestors with rocks and sticks.

The so-called thugs—baltagiya in Arabic—have broken up a number of demonstrations in recent months. Protestors say the thugs are paid mercenaries hired by the military. The military says they are angry local residents who don´t want the demonstrators coming to their neighborhood.

By nightfall, plumes of smoke were rising from the streets in front of the defense ministry headquarters. The Ministry of Health said 296 people were wounded in the clashes, according to state television, and one member of the security forces was killed.

Late Friday night, there were signs that some groups involved in the clashes were seeking calm. In Abbasiya, the neighborhood where they occurred, the military imposed an 11 p.m. to 7 a.m. curfew. A member of the ruling military council, Gen. Mukhtar al-Mulla, said in a televised address that the military would "decisively confront" any violations of the curfew.

Meanwhile a prominent hardline Salafi group, the Gamaa Islamiya, denounced the violence in a statement and urged protestors to confine themselves to Tahrir Square, where protests have generally been permitted in recent months.


The April 6 movement, a group of more secular-minded revolutionaries who were among those involved in Friday´s clashes, called for followers to withdraw from the flashpoint in Abbasiya, in a statement.

It remains unclear how the violent flareups will impact Egypt´s presidential elections. During similar outbursts of violence in the runup to parliamentary elections last fall, many candidates´ supporters were directly involved in the violence.

But Egypt´s leading presidential contenders have mostly kept their distance from the latest violence, with some going about their routine campaign activities even as the clashes were raging. —Summer Said contributed to this article. (Copyright © Dow Jones & Company, Inc.) 05/05/12)