Police officers firing tear gas joined with a rock-throwing crowd fighting a group of Christian mourners Sunday in a battle that escalated into an attack on Egypt's main Coptic Christian Cathedral that lasted for hours. It was the third day of an outburst of sectarian violence that is testing the pledges of Egypt's Islamist president to protect the country's Christian minority. By nightfall, at least one person had died from the day's clashes, bringing the weekend's death toll to six. Later Sunday, President Mohamed Morsi called the Coptic pope, Tawadros II, to reassure him. “I consider any aggression against the cathedral an aggression against me personally," Mr. Morsi said, according to state media. The president ordered an investigation of the violence and instructed security forces “to protect the citizens inside the Cathedral," state media reported, and he pledged to protect both Muslims and Christians. The violence began Friday when a sectarian dispute in the town of Khusus outside Cairo escalated into a gunfight that killed four Christians and a Muslim — the first major episode of deadly sectarian violence since Mr. Morsi's election last year. Hundreds of Christians and sympathetic Muslims gathered at the cathedral Sunday for the four Christians' funeral, chanting for the removal from power of Mr. Morsi and his Islamist allies. “With our blood and our soul we will sacrifice ourselves for the cross," the crowd intoned. Clashes erupted immediately after the service between the emerging mourners and a crowd outside the cathedral. It was unclear who started the violence. But later dozens of riot police with armored vehicles and tear-gas canons appeared to enter the fray on the side of crowds of young Muslim men who were throwing rocks and fire bombs at the mourners. In what seemed like a siege of the cathedral, tear-gas canisters fell inside the walls of its compound, sending gas into the sanctuary and two nuns running for shelter in a nearby loading dock. Later, some of the young civilians who had been attacking the cathedral switched to taunts, making lewd gestures involving the sign of the cross. The riot policemen made no attempt to stop them, either from throwing rocks toward the cathedral or insulting the Christians. “The police are not trying to protect us or do anything to stop the violence," said Wael Eskandar, a Coptic Christian activist. “On the contrary, they are actively aiding the people in civilian clothes" attacking the Christians, he said. Dozens rushed to defend the cathedral, and many pulled back their sleeves at the iron entrance gate to display the cross that many Copts tattoo on their wrists. Groups of young men stood on the cathedral walls and rooftops nearby, throwing fire bombs and the shards of bricks at the riot police. At least two of the young men on the church grounds carried what appeared to be crude pistols. Others prepared crates full of fire bombs. The Interior Ministry, in a statement on its Web site, said the mourners had started the violence and that the riot police intervened to stop it. “Some mourners vandalized a number of cars, which led to clashes and fights with the people of the area," the statement said, adding, “Interference to separate the clashing parties is ongoing." Coptic Christians, who make up about 10 percent of Egypt's roughly 85 million citizens, were already anxious about the dominance of elections by the Islamist Muslim Brotherhood since the ouster of President Hosni Mubarak, the former secular autocrat. Not that sectarian animosities were absent under Mr. Mubarak. Copts suffered from discrimination as well as recurring episodes of sectarian violence, and the Mubarak government worsened the problem by denying the existence of domestic sectarianism and pinning blame on either local conflicts or foreign conspiracies. Mr. Morsi and the Muslim Brotherhood have sometimes appeared to understand that as Islamists they have more to prove to Egypt's Copts. During elections, Brotherhood candidates have emphasized their commitment to equal citizenship and security for Copts, even sending young Brotherhood members to stand guard outside churches at a Christmas service one year. When a dispute over a shirt burned at the laundry exploded into a sectarian battle that killed a Christian and damaged several properties last year, Mr. Morsi departed from the Mubarak script, sending a legal adviser to meet with the Christians, instructing the local governor to compensate the victims and asking the prosecutor to investigate without prejudice. But on Sunday, many Copts blamed Mr. Morsi for the violence. “Who is responsible for the surroundings of the cathedral being unsecured for more than five hours today?" demanded Bishop Bakhomious, a senior Coptic cleric who had been acting pope until the designation of Tawadros II. “If the security services want to know who is behind these events, they will." It is unclear how much practical control Mr. Morsi exercises over the police. He has done little to reform the force left over from Mr. Mubarak despite continuing complaints about its abuses. A rash of police strikes has showcased widespread insubordination, and the riot police lack training in effective crowd control. On Sunday, they sometimes appeared to fire tear gas at random into the surrounding neighborhood. But even before the police joined the fray, human rights advocates said Mr. Morsi and his party had failed to confront the sectarianism driving the violence. Until late Sunday, both Mr. Morsi and his party appeared to fall into the Mubarak pattern, denouncing the violence but without acknowledging the problem of sectarianism. Instead, the Islamists suggested a conspiracy by some unknown party to sow dissent among Egyptians. Only on Sunday night, after the clashes had subsided, did Mr. Morsi publicly acknowledge the role of sectarian aggression or personally pledge to protect the Copts. “He seems to have begun to realize the scale of this," said Hossam Bahgat, founder of the Egyptian Initiative for Personal Rights.
