A bombing near the Coptic cathedral in the Egyptian capital Cairo has killed at least 25 people, officials say.
Dozens of others were injured in the blast at St Peter’s church during a Sunday church service.
The church is adjacent to St Mark’s cathedral, within the same complex. Photos and video footage showed damage to the church, with shattered windows and broken roofing.
Three days of national mourning have been declared.
The explosion happened at 10:00 (08:00 GMT). Video footage carried by regional media showed the interior of the church littered with broken and scattered furniture, along with blood and clothing on the floor.
“I saw a headless woman being carried away,” one eyewitness told the Associated Press news agency. “Everyone was in a state of shock.”
“There were children. What have they done to deserve this? I wish I had died with them instead of seeing these scenes,” she said.
President Abdul Fattah al-Sisi has declared a three-day period of national mourning.
He condemned the attack, calling for the perpetrators to be punished, local television reported.
“Vicious terrorism is being waged against the country’s Copts and Muslims. Egypt will emerge stronger and more united from this situation,” he was quoted as saying.
Coptic Christians make up about 10% of Egypt’s population.
St Mark’s Cathedral is the headquarters of the Coptic Orthodox church, and the home of its leader, Pope Tawadros II.
What is the Coptic Christian faith?
The Coptic Orthodox Church is the main Christian Church in Egypt. While most Copts live in Egypt, the Church has about a million members outside the country.
Copts believe that their Church dates back to around 50 AD, when the Apostle Mark is said to have visited Egypt. Mark is regarded as the first Pope of Alexandria – the head of their church.
This makes it one of the earliest Christian groups outside the Holy Land.
The Church separated from other Christian denominations at the Council of Chalcedon (451 AD) in a dispute over the human and divine nature of Jesus Christ.
The early Church suffered persecution under the Roman Empire, and there were intermittent persecutions after Egypt became a Muslim country. Many believe that continues to this day.
Bishop Angaelos of the UK’s Coptic Orthodox Church said his prayers were with Egyptian Copts, “as well as for the broader Egyptian society that fall victim to similar inhumane attacks.”
On Saturday, six policemen were killed when a bomb exploded on a main road leading to the pyramids at Giza. The explosion, at a police checkpoint, was the deadliest attack on security forces in Cairo in over six months.
A recently formed militant group called Hasm said it carried out the attack.
Egypt’s Coptic Christian minority have complained of discrimination in the mostly Muslim nation.
Two people were killed outside St Mark’s cathedral in 2013, when people mourning the death of four Coptic Christians killed in religious violence clashed with local residents.
In February this year, a court sentenced three Christian teenagers to five years in prison for insulting Islam. The teenagers had appeared in a video, apparently mocking Muslim prayers, but claimed they had been mocking the Islamic State group following a number of beheadings.
Egypt has pursued a number of blasphemy cases since the country’s 2011 uprising. Many of those cases have been against Copts.
President Sisi, then head of the army, seized power in 2013, and won a presidential election a year later. He outlawed the Muslim Brotherhood, and has been battling insurgent Islamic groups ever since.
Most of the militant attacks have been focused in the Sinai province, where an IS-linked jihadist group is active, but Cairo has also suffered a string of attacks in the past two years.