Photo: A nun cries as she stands at the scene inside Cairo's Coptic cathedral, following a bombing Sunday. | REUTERS

CAIRO — A bomb ripped through Cairo’s Coptic cathedral complex during Sunday Mass, killing at least 25 people and injuring 49, and delivering the bloodiest attack on Egypt’s Christian minority in recent years, according to Egyptian officials and Christian community leaders.

The explosion unfolded inside St. Mark’s Coptic Orthodox Cathedral at the 100-year-old Botrosiya Church, also known as the Church of St. Peter and St. Paul, shortly after the 200 or so worshipers had stopped reading Bible verses and the priest was getting to ready to start his sermon, witnesses said.

About 9:45 a.m., “everything turned black suddenly,” Qelliny Farag said.

As of Sunday evening, there had been no claims of responsibility. But suspicion immediately fell on Islamist extremists, including Egypt’s Islamic State branch, who have staged numerous attacks across the country this year targeting soldiers, police and government officials. Sunday’s carnage came less than 48 hours after a bomb killed six police officers and injured an additional three on a road leading to Egypt’s famed Great Pyramids complex.

The bombing came on a public holiday here, commemorating the birthday of the prophet Muhammad.

Although that is a Muslim celebration, the church was filled with more than the usual number of congregants taking advantage of the day off.

When the bomb detonated, Farag, 80, was seated on the left side of the church. His wife, Samiha Tawfik, was on the right side, along with the other female congregants.

“I could not see anything,” Farag said. “We were all in shock, covered in dust, running through corpses that got thrown by the intensity of the blast.”

Unable to breathe from the dust, his head pounding, he stumbled around the pews. Soon, he began to see, and understand, what had happened.

“A minute passed by and I started to see flesh scattered everywhere around us,” he said. “Even the ceiling had collapsed.”

He couldn’t find his wife.

Egypt’s Orthodox Coptic Christian community, which makes up 10 percent of the population, has long felt discrimination at the hands of the country’s Muslims, as well as successive secular but authoritarian regimes. Attacks on Christians have intensified since the 2011 populist revolt that ousted President Hosni Mubarak. At least 26 sectarian assaults have targeted the community this year alone, according to human rights activists.

Sunday’s bombing was the gravest sectarian attack on Christians in recent years. The cathedral complex houses the headquarters of the Coptic Orthodox Church in Egypt, as well as the home of its leader, Pope Tawadros II.

Over the past six years, numerous attacks on Christians have left scores dead. On Jan. 1, 2011, the Church of Saints Mark and Peter in the northern city of Alexandria was bombed, killing 23 people as they left the New Year’s Day service. Ten months later, Egypt’s security forces killed 28 Christians protesting the demolition of a church, claiming the protesters first attacked them.

In 2013, Christians were targeted in a spate of attacks after Egypt’s elected Islamist president, Mohammed Morsi, was ousted in a military coup.

President Abdel Fattah al-Sisi, the former general who led the coup, condemned Sunday’s attack and declared three days of mourning.

“Vicious terrorism is being waged against the country’s Copts and Muslims,” he was quoted as saying on local television networks. “Egypt will emerge stronger and more united from this situation.”

In Washington, the State Department said that the “United States condemns in the strongest possible terms the terrorist attack today on Christian worshipers outside St. Mark’s Cathedral.” In New York, the U.N. Security Council likewise condemned “the heinous and cowardly terrorist attack.”

Analysts focusing on Egypt’s religious divides said the government has made previous promises to apprehend the perpetrators of hate crimes. But it has shown few results.

“Sectarian tensions in Egypt is ongoing and this attack, although shocking in its scope, is not an aberration,” said Amira Mikhail, a fellow at the Tahrir Institute for Middle East Policy. “Despite the shift in public rhetoric by President Sisi in which he has called for religious reform and has visited the cathedral on several occasions, little has been done to actually change the institutionalized sectarianism in the government and the continued violence perpetrated by nonstate actors.”

Some reports on local television networks suggested that a bomb was concealed inside a handbag in a section of the church designated for female worshipers. A large proportion of the victims were women, according to local reports.

Senior Egyptian officials, including the prime minister and interior minister, arrived at the church shortly after the attack. They were greeted by a small group of angry protesters who railed against the continual attacks on Christians, as well as security forces’ failure to stop the attacks.

“The police are thugs,” some in the crowd chanted.

“The people demand the removal of the regime,” others shouted.

Farag and other witnesses said they noticed no police or guards at the entrance to the church, although there is typically a heavy security presence at the cathedral to provide protection for the pope.WP