CAIRO, Dec. 11 (UPI) — A bomb exploded inside a Coptic Christian church Sunday morning, killing at least 25 and injuring 49, Egyptian state television said.

The blast took place as Sunday Mass was nearing an end at 10 a.m. and coincided with a national holiday in Egypt marking the birth of Islam’s Prophet Muhammad.

The Rev. Paul Halim, the Coptic Church’s official spokesperson, told Al-Ahram Arabic news website that the explosion took place in the small church of St. Peter and St. Paul complex, attached to the Coptic Cathedral in Cairo’s Abbassyia district.

A device detonated about 26 pounds of TNT on the women’s side of the church, security sources said. Most of the victims were women.

No one has claimed responsibility.

The 100-year-old women’s chapel, named after the former U.N. Secretary-General Botros Ghaly, is adjacent to St. Mark’s cathedral, which was undamaged.

“Human remains were everywhere. The dead bodies were scattered. Some people’s heads had been cut off,” Qelleny Farag, 80, who was at the mass with his wife during the explosion, told The Telegraph.

Qelleny, who was uninjured, said he could not find his wife.

Hospitals where the injured are being treated have called for blood donations.

President Abdul Fattah al-Sisi has declared a three-day period of national mourning.

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

On Friday, an explosion killed six police officers and injured three others in Giza’s Haram district and another was in Kafr El-Sheikh international road, killing one civilian and injuring three police officers.

“Today’s terrorist attack is a direct attempt to derail Egypt’s economy in need of foreign investments and to also deter tourists from visiting the country,” Adel El-Adawy, Ph.D candidate at the Department of War Studies, King’s College London told Al Arabiya English.

In 2011, the previous worst attack against Copts was when 23 people were killed in an explosion at the Two Saints Church in Alexandria.

Coptic Christians are about 10 percent of Egypt’s 80 million residents, the CIA’s World Factbook states.

The church separated from other Christian denominations in 451 A.D. in a dispute over the human and divine nature of Jesus Christ.