Updated

Questions and answers about Wednesday's violence in Cairo, in which at least 11 people were killed in clashes between suspected supporters of Egypt's military rulers and anti-government protesters three weeks before presidential elections.

Q: Who is in the streets?

A: The protesters who were attacked were mainly Islamists from the ultraconservative Salafi movement. They have been holding a sit-in for days near the Defense Ministry, protesting the disqualification of their candidate Hazem Abu Ismail from the presidential race by the military-appointed election commission.

Unlike the mass rallies last year by hundreds of thousands of all political stripes during the uprising that ousted Hosni Mubarak, this protest rarely approached 1,000 people. Some other groups joined in solidarity against the military, but the rally's small size showed most activists' reluctance to ally themselves with the hard-line Islamist crowd.

Q: So why attack them?

A: The attackers' motive — and their identity — is unclear. Some claim residents of the neighborhood, Abbasiyah, lashed out in anger over the protest. But others believe they were hired thugs, noting their apparent experience with firearms. The fact that troops close by did nothing to stop the attacks for hours has raised accusations from some that the ruling military was ultimately to blame.

That has unleashed a storm of conspiracy theories. Some fear the generals are trying to create chaos as a pretext for delaying presidential elections set to begin May 23. Others think they are sending a signal to Islamists to back down in the Islamist-military confrontation that has been growing for weeks.

The military denies any hand in the latest violence and so far is saying elections will go on as scheduled, followed by the handover of power from the generals to the winner.

Q: What is the political backdrop to the tensions?

A: There are three front-runners among the 13 presidential candidates. They are Mubarak's former foreign minister Amr Moussa, the Muslim Brotherhood's Mohammed Morsi, and a moderate Islamist, Abdel-Moneim Abolfotoh.

Many fear that no matter who wins, the military's goal is to retain its privileged position and a degree of say in politics, even after it formally hands over power.

Tensions have been growing between the military and the Muslim Brotherhood, which has become Egypt's strongest political movement in the post-Mubarak transition. The Brotherhood has been frustrated that its control of nearly half of parliament has not translated into real political power. So it has stepped up demands that the generals remove the military-appointed prime minister and let the Brotherhood form a government. The generals have refused. The Brotherhood's moves have prompted a backlash in some quarters, including among some who backed it in parliament elections late last year but now accuse it of a power grab that endangers the transition.

The power struggle boils down to three main groups. There is the Muslim Brotherhood, already dominating parliament and seeking the presidency as well. There is the military, which may be trying to ensure a candidate amenable to its aims holds the presidency. And finally, there are liberal, leftist and secular groups, which drove last year's uprising but have not made strong showings in elections so far. They — and even some Islamists — are concerned about the Brotherhood gaining too much power but also do not want to see the generals keep their authority.

Q: What happens now?

A: A number of groups are now moving to join the protesters outside the Defense Ministry. The Muslim Brotherhood and other parties have called for a mass protest on Friday in Cairo's Tahrir Square to demand the generals abide by promises to hand over power.

The short presidential election campaign could see turbulent protests on top of the political maneuvering.