A fire ripped through a packed church during morning services in Egypt’s capital on Sunday, killing at least 41 worshippers and injuring 14.

The church quickly filled with thick black smoke, and witnesses said several trapped congregants jumped from upper floors to escape. “Suffocation, suffocation, all of them dead,” said a distraught witness, who only gave a partial name, Abu Bishoy.

The cause of the blaze in the Abu Sefein church in the working-class neighborhood of Imbaba was not immediately known. An initial investigation pointed to an electrical short-circuit, according to a police statement.

Footage from the scene circulated online showed burned furniture, including wooden tables and chairs. Firefighters were seen putting out the blaze while others carried victims to ambulances. Families waited for word on relatives who were inside the church.

Witnesses said there were many children inside the building when the fire broke out.

“There are children we didn’t know how to get to them,” said Abu Bishoy. “And we don’t know whose son this is, or whose daughter that is. Is this possible?”

The country’s health minister blamed the smoke and a stampede as people attempted to flee the fire for causing the fatalities. It was one of the worst fire tragedies in Egypt in recent years.

Witness Emad Hanna said the church includes two places used as a daycare for children, and that a church worker managed to get many children out.

“We went upstairs and found people dead. And we started to see from outside that the smoke was getting bigger, and people want to jump from the upper floor. ... We found the children.”

Egypt’s Coptic Church and the country’s health ministry reported the casualty toll. The church said the fire broke out while a service was underway. The church is located in a narrow street in one of the most densely populated neighborhoods in Cairo.

Fifteen firefighting vehicles were dispatched to the scene to put out the flames while ambulances ferried casualties to nearby hospitals, officials said.

President Abdel Fattah el-Sissi spoke by phone with the Coptic Christian Pope Tawadros II to offer his condolences, the president’s office said. Sheikh Ahmed al-Tayeb, Al-Azhar’s Grand Imam, also offered his condolences to the head of the Coptic church.

“I am closely following the developments of the tragic accident,” el-Sissi wrote on Facebook. “I directed all concerned state agencies and institutions to take all necessary measures, and immediately to deal with this accident and its effects.”

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Health Minister Khaled Abdel-Ghafar said in a statement that two of the injured were discharged from a hospital while 12 others were still being treated.

The Interior Ministry said it received a report on the fire at 9 a.m. local time, and that they found that the blaze broke out in an air conditioner in the building’s second floor.

The ministry, which oversees police and firefighters, blamed an electrical short-circuit for the fire, which produced huge amounts of smoke. Meanwhile, the country’s chief prosecutor, Hamada el-Sawy, ordered an investigation and a team of prosecutors were dispatched to the church.

Later on Sunday, emergency services said they managed to put out the blaze and the prime minister and other senior government officials arrived to inspect the site.

Egypt’s Christians account for some 10% of the nation’s more than 103 million people and have long complained of discrimination by the nation’s Muslim majority.

Sunday’s blaze was one of the worst fire tragedies in recent years in Egypt, where safety standards and fire regulations are poorly enforced. In March last year, a fire at a garment factory near Cairo killed at least 20 people and injured 24 more.