CAIRO — Egypt was in mourning Monday over a blaze at a Coptic Orthodox church that killed 41 people, but many also raised questions about the emergency response, fire safety codes, and restrictions on building houses of worship for the country’s Christian minority.

Neighborhood residents expressed shock over the fire Sunday, one of Egypt’s deadliest in recent years, that killed 41 members of the congregation, including at least 15 children.

“The scene of dead children still haunts me,” said Salah el-Sayed, a 43-year-old civil servant who lives next to the Martyr Abu Sefein church in the working-class Imbaba neighborhood, and was one of the first to arrive at the scene as thick smoke poured from the building.

“Bodies of children littered everywhere,” he said.

The fire broke out during Sunday morning services, beginning on the second floor of the four-story building, which also housed a day care. Smoke quickly engulfed the upper floors.

Authorities blamed an electrical short-circuit in an air conditioner unit for the fire, but witnesses also pointed to a fault in a power generator which the church used during regular power outages. People also said ambulances were slow to arrive, which could have caused more deaths, although authorities said the first ambulance arrived within minutes after the fire was reported.

Witnesses speaking to The Associated Press recounted horrific scenes of people jumping out of windows, a stampede in the church’s main hall and stairs, and children lying motionless amid fire and burned furniture.

El-Sayed, who with others rushed to the church to rescue trapped worshippers and carried bodies to waiting ambulances, said electricity was down for about half an hour that Sunday morning. He saw smoke rising minutes after the current returned.

The thick smoke made it difficult for them to get inside, and some rescuers jumped from the roof of an adjacent building. Others stormed the church front gate and made their way upstairs where the children were trapped on the fourth floor.

Ahmed Ibrahim, who lived nearby, said he saw a man trying to jump from a second floor window. He and others tried to save the man’s life by holding out a blanket, but the man fell to the ground and died.

“Unfortunately he was heavy,” Ibrahim said. “It was frustrating.”

Mohammed Yahia was among those who ran to the church, heading immediately to the day care.

Of the 20 children inside the day care, he said all but five died, speaking to a local television station from a hospital bed. Yahia carried five bodies — one by one — to the ambulances, before he fell and broke his leg while helping an elderly person out of the building.

The dead children included siblings, twins aged 5 and a 3-year-old. Five-year-old triplets, their mother, grandmother and an aunt were also among those killed, according to Mousa Ibrahim, a spokesman for the Coptic Orthodox Church. Images of the dead children went viral on social media.

The church bishop, Abdul Masih Bakhit, was also among the dead.

The church is located on a narrow street in one of Cairo’s most densely populated neighborhoods. It was an apartment building before it was turned into a church like many others across the country, according to neighbors. It looks like other buildings in the area, recognizable only by a sign above its front door, and an iron cross on its roof.

Coptic Christian Pope Tawadros II said Martyr Abu Sefein, like many others, is too small for the number of congregants it serves. In televised comments late Monday, he urged authorities to find solutions to build more churches.

Anba Angaelos, the archbishop of the Coptic Orthodox Church in London, blamed restrictions on church construction that have forced Christians to convert residential buildings into places of worship.

The tragedy “is a direct result of a painful time when Christian communities could not build purpose-designed churches, and would have to covertly use other buildings, not fit for the purpose and lacking the necessary health and safety features and escapes,” he wrote Sunday on Twitter.

Church-building has for decades been one of the most sensitive sectarian issues in Egypt, where 10% of the population of 103 million are Christians, but where Muslim hard-liners sharply oppose anything they see as undermining what they call the country’s “Islamic character.”

In the past, local authorities had often refused to give building permits for new churches, fearing protests and riots by Muslim ultraconservatives. Amid such restrictions, Christians turned to building illegally or setting up churches in other buildings, such as the case of Martyr Abu Sefein.

Many similar churches lack licenses and are not up to safety code. In recent years, the government of President Abdel Fattah el-Sissi has sought to regulate church building. In 2016, the government issued the country’s first law spelling out the rules for building a church, though critics argued that the legislation is in line with previous restrictions.

On Monday, a senior government official said authorities, in coordination with the Coptic Orthodox Church, would review all safety measures in churches across the country especially those in Cairo slums. The official spoke on condition of anonymity because he was not authorized to speak to the media.

Some relatives of victims and witnesses said ambulances and firefighters took too long to arrive, but Health Minister Khaled Abdel-Ghaffar said that the first ambulance arrived at the site two minutes after the fire was reported.

The street where Martyr Abu Sefein church is located remained cordoned off Monday as construction workers worked to clear away debris.