Mobs set two churches on fire in western Cairo during sectarian clashes that left 10 dead and were triggered by rumors of an interfaith romance, in the latest incident of Muslim-Christian violence since a popular uprising ousted the president.

Egypt's prime minister canceled his visit to the Gulf on Sunday, and called for an emergency Cabinet meeting to discuss the violence, according to the state news agency.

Saturday night's clashes were sparked by rumors in the low-income neighborhood of Imbaba that a Christian woman married to a Muslim had been abducted and was being held in one of the churches against her will.

The report, which was never confirmed, spurred a mob from the ultraconservative Salafi trend of Islam to march on the Saint Menas Church. Christians barricaded themselves inside and around the church and the demonstrations turned violent. Gunfire sounded across the neighborhood, and witnesses said people on rooftops fired into the crowd.

The Muslims, spurred on by the local Salafi religious leaders converged on the area, lobbing fire bombs at homes, shops and the church, setting its facade on fire.

The crowd later attacked another nearby church, the Virgin Mary Church, and set it on fire as well. The army and police tried to disperse the crowds with tear gas, but failed to clear the streets for hours.

Residents stormed a six-story building near the Saint Menas Church, also setting it on fire, claiming the Christians used it to shoot at Muslims.

"They were shooting from the roof, and they killed Muslims," said 18-year old Yehia Ramadan. "We won't stand idly by."

On Sunday morning, flames were still shooting out of windows, and furniture was strewn along the sidewalks.

The fires in the churches were eventually extinguished and the buildings were surrounded by the army. Residents say Christians were hiding inside.

The attackers chanted "With our blood and soul, we defend you Islam."

Egypt's state news agency said six Muslims and three Christians were killed. The body of one Christian was found inside the church. The religion of a 10th victim was not clear. Hisham Sheiha, a Health Ministry official, told the news agency that 186 were injured, including 11 in critical condition from gunshot wounds.

Interfaith relationships are taboo in Egypt, where the Muslim majority and sizable Christian minority are both largely conservative. Such relationships are often the source of deadly clashes between the faiths.

If a Christian woman marries a Muslim, she is expelled from the church. A Muslim woman is not allowed to marry a Christian man, according to state law.

Because divorce is banned under the Coptic Church, with rare exceptions, some Christian women resort to conversion to Islam or another Christian denomination to get out of a marriage.

Sameh Fawzi, a Coptic scholar, said the new trend of attacks on churches and heightened tension between ultraconservative Muslims and Copts are taking place in the context of a weakened state and increasingly assertive Salafis. Afterwards, attempts to hold reconciliation sessions, instead of prosecuting those involved, only serve to reinforce the state weakness, he said.

"What needs to happen and quickly is that the state implements the law," he said. "This is a crime of thuggery and it should be treated as such."

There have been sporadic attacks on Christians and their houses of worship over the years, mostly in the impoverished south of the country and in many cases, those involved are not brought to justice.

Ultraconservative Salafi Muslims have been protesting for almost a year over the alleged church abduction of a priest's wife because, they claim, she converted to Islam to escape an unhappy marriage _ a phenomenon they maintain is common.

Salafis have used the case of Camilla Shehata as a rallying point for their supporters and they accuse the police of collaborating with the church to reconvert her.

On Saturday just before the violence in Imbaba, Shehata appeared with her husband and child on a Christian TV station broadcast from outside of Egypt and asserted that she was still a Christian and had never converted.

"Let the protesters leave the Church alone and turn their attention to Egypt's future," she said from an undisclosed location.

Since the fall of Egypt's authoritarian government in a popular uprising, the once quiescent Salafis have become more assertive in trying to spread their ultraconservative version of an Islamic way of life.

Their protests have inflamed the already delicate state of religious relations in Egypt.

The Coptic Christian minority makes up 10 percent of Egypt's 80 million people and complains of widespread discrimination that they say relegates them to second-class citizen status.

A Jan. 1 suicide bombing outside a Coptic church in the port city of Alexandria killed 21 people, setting off days of protests. Barely a week later, an off-duty policeman shot and killed a 71-year-old Christian man, and wounded his wife and four others.

In the deadliest violence since the February ouster of the president, 13 were killed in pitched street battles in March after Muslims torched a church, once again over rumors of a love affair between a Muslim woman and a Christian man.

Islamic clerics denounced the violence, sounding alarm bells at the escalating tension during the transitional period.

The head of al-Azhar said the prestigious Islamic institution condemns the violence. "These events do not benefit either Muslim or Copts," Ahmed al-Tayyeb, the Sheik of al-Azhar told the daily Al-Ahram.