Egyptian President Abdel-Fattah el-Sissi said Monday that a suicide bomber caused the blast that killed 24 Christians during Sunday Mass at a Cairo chapel adjacent to St. Mark's Cathedral, the seat of Egypt's ancient Coptic Orthodox Church.
It was among the deadliest attacks to ever target Egypt's Coptic minority, which makes up around 10 percent of the country's population and strongly supported the military overthrow of an elected Islamist president in 2013, which was led by el-Sissi.
Since then, Islamic militants have carried out scores of attacks mainly targeting the security forces, while the government has waged a wide-scale crackdown on dissent.
Speaking after a state funeral for the victims, el-Sissi identified the bomber as 22-year-old Mahmoud Shafiq Mohammed Mustafa, and said three men and a woman were arrested in connection with the attack, which wounded 49 people. Two other suspects were on the run, he added.
El-Sissi did not link the bomber to any militant groups, but a top Interior Ministry official -- police Maj. Gen. Tarek Attia -- told The Associated Press that he was arrested in Fayoum province, southwest of Cairo, in 2014 on charges of being a member of the outlawed Muslim Brotherhood.
The president spoke after Health Ministry officials revised down the number of victims to 24, suggesting that the 25th body belonged to the bomber. The victims are thought to include 22 women.
No group has claimed responsibility for the attack.
"This strike really hurt us and caused us much pain, but it will not break us," el-Sissi said. "God willing, we will win this war."
He also called on the government and parliament to introduce legislation that would allow more "decisive" methods of dealing with militants. He did not elaborate.
"As long as we are together as one, we will definitely win, because we are people of goodness, not evil, and people of building, not destruction," he said.
The coffins were wrapped in Egyptian flags. Pope Tawadros II, spiritual leader of Egypt's Orthodox Christians, and top government and military officials attended the funeral, held amid tight security provided by hundreds of army soldiers. Earlier on Monday, the Coptic community held its own funeral service.
"God, protect us and your people from the conspiracies of the evil ones," Tawadros prayed after waving incense over coffins lined up in front of the altar along with crosses made of white roses. "It is the destiny of our church to offer martyrs."
Only victims' relatives were allowed to attend the service at the Virgin Mary and St. Athanasius church in the eastern Cairo suburb of Nasr City. Some screamed out in grief or shouted out victims' names, while the rest sat in silence or quietly wept.
Outside the church, a crowd scuffled with security forces when they were barred from attending the service. An unspecified number of arrests were made, several witnesses said, speaking on condition of anonymity because they feared for their safety.
"People have a volcano of anger inside their chests," said Nora Sedki, a Christian government employee who joined a demonstration of several hundred protesters outside the church.
"The blood of our brothers is dear," chanted the protesters, who carried Egyptian flags and crosses made of tree branches.
Egypt has seen a wave of attacks by Islamic militants since 2013, when the military overthrew President Mohammed Morsi of the Brotherhood amid mass protests against his divisive rule.
Many of his supporters lashed out at Christians after his ouster, ransacking and destroying scores of churches and Christian-owned properties in southern Egypt, where sectarian tensions are more pronounced.
For decades, Christians have complained of discrimination, saying they are denied top jobs in many fields, including academia and the security forces. They have also accused the security forces of failing to do enough to protect them from Muslim extremists, a complaint that has persisted under el-Sissi's rule.