Updated

At least 36 people detained on suspicion of taking part in Egypt's street clashes died Sunday when they tried to escape from a prison truck convoy in Cairo, security officials say, as the country's military leader vowed to tolerate no more violence.

The officials, who spoke to the Associated Press on condition of anonymity, said those killed -- which included members of the Muslim Brotherhood -- were part of a convoy of some 600 detainees heading to Abu Zaabal prison in northern Egypt.

The officials said detainees in one of the trucks rioted and managed to capture and attack a police officer inside. Security forces responded with tear gas, hoping to freeing the badly beaten officer, but the gas ended up suffocating 36 of the detainees, the officials added.

Egypt's Interior Ministry supported the officials' description of the events, according to Reuters, but did not say how many people were killed.

However, the country's official news agency, MENA, offered a different account of the violence.

MENA reports that gunman belonging to the Muslim Brotherhood approached the trucks and exchanged fire with guards. Thirty-six Muslim Brotherhood detainees then died in the gunfire as they tried to escape, MENA said.

The differences in the accounts could not be immediately reconciled Sunday night.

The deaths came after Egyptian authorities raided the homes of Muslim Brotherhood members , detaining hundreds of mid-level officials in a bid to crack down on attacks on Christian churches and businesses. The group had plans for marches in Cairo, but cancelled them later in the day, claiming that snipers were positioned on rooftops along the routes.

Egypt's military leader, Gen. Abdel-Fatah el-Sissi, said Sunday during a gathering of top military commanders and police chiefs that the army will not stand by silently in the face of violence. It was El-Sissi's first appearance since the deadly crackdown on Wednesday.

He also said that the Army has no intention to seize power, while calling on Islamists to join the political process.

"We will not stand by silently watching the destruction of the country and the people or the torching the nation and terrorizing the citizens," he said in comments quoted on state television and posted on an official military Facebook page. "We have given many chances ... to end the crisis peacefully and call for the followers of the former regime to participate in rebuilding the democratic track and integrate in the political process and the future map instead of confrontations and destroying the Egyptian state."

A military timetable calls for the nation's constitution to be amended and for presidential and parliamentary elections to be held in 2014.

Since security forces cleared two sit-in camps filled with supporters of former President Mohammed Morsi on Wednesday, Islamists have attacked dozens of Coptic churches, along with homes and businesses owned by the Christian minority. The campaign of intimidation appears to be a warning to Christians outside Cairo to stand down from political activism.

At least 300 Muslim Brotherhood officials and field operatives were detained in several cities during Sunday's raids, security officials and group statements said.

In Assiut, 200 miles south of Cairo, 163 of the group's officials and operatives were rounded up in different towns in the province, security officials said. They said those arrested face charges of instigating violence and orchestrating attacks on police stations and churches.

In the city of Suez, nine people were arrested after being caught on film attacking army vehicles, burning churches and assaulting Christian-owned stores, officials said. And in Luxor, more than 20 Brotherhood senior officials were detained, officials said.

The Muslim Brotherhood, which has launched protests since Morsi's July 3 ouster by the military, scuttled plans for two Sunday demonstrations in Cairo.

Prior to the cancellations, authorities stationed armored vehicles and troops in front of the Supreme Constitutional Court courthouse in Cairo, which may have turned into another focal point of street violence.

Sources in the Muslim Brotherhood told the BBC that the protests were canceled because of the presence of snipers on buildings along the routes of the marches," although the claim could not be verified.

Christians have long suffered from discrimination and violence in Egypt, where they make up 10 percent of the population of 90 million. Attacks increased after the Islamists rose to power in the wake of the 2011 Arab Spring uprising that drove Hosni Mubarak from power, emboldening extremists. But Christians have come further under fire since Morsi was ousted on July 3, sparking a wave of Islamist anger led by the Muslim Brotherhood.

Many Morsi supporters say Christians played a disproportionately large role in mass rallies that occurred before Morsi was ousted by the military, as millions took to the streets to demand Morsi's resignation.

Despite the violence, Egypt's Coptic Christian church renewed its commitment to the new political order Friday, saying in a statement that it stood by the army and the police in their fight against "the armed violent groups and black terrorism."

Some Christians have also drawn closer to moderate Muslims in a few provinces, in a rare show of solidarity.

Hundreds from both communities thronged two monasteries in the province of Bani Suef south of Cairo to thwart what they had expected to be imminent attacks on Saturday, local activist Girgis Waheeb said. Activists reported similar examples elsewhere in regions south of Cairo, but not enough to provide effective protection of churches and monasteries.

Waheeb, other activists and victims of the latest wave of attacks blame the police as much as hard-line Islamists for what happened. The attacks, they said, coincided with assaults on police stations in provinces like Bani Suef and Minya, leaving most police pinned down to defend their stations or reinforcing others rather than rushing to the rescue of Christians under attack.

Another Christian activist, Ezzat Ibrahim of Minya, a province also south of Cairo where Christians make up around 35 percent of the population, said police have melted away from seven of the region's nine districts, leaving the extremists to act with near impunity.

Sister Manal, the 47-year-old principal of the Franciscan school in Bani Suef, told the Associated Press that she was having breakfast with two visiting nuns when news broke of Wednesday's crackdown on the Cairo sit-ins. In an ordeal that lasted about six hours, she, sisters Abeer and Demiana and a handful of school employees saw a mob break into the school through the wall and windows, loot its contents, knock off the cross on the street gate and replace it with a black banner resembling the flag of Al Qaeda.

By the time the Islamists ordered them out, fire was raging at every corner of the 115-year-old main building and two recent additions. Money saved for a new school was gone, said Manal, and every computer, projector, desk and chair was hauled away. Frantic SOS calls to the police, including senior officers with children at the school, produced promises of quick response but no one came.

Manal recalled being told a week earlier by the policeman father of one pupil that her school was targeted by hard-line Islamists convinced that it was giving an inappropriate education to Muslim children. She paid no attention, comfortable in the belief that a school that had an equal number of Muslim and Christian pupils could not be targeted by Muslim extremists. She was wrong.

Bishoy Alfons Naguib, a 33-year-old businessman from Minya, had a similarly harrowing story.

His home supplies store on a main commercial street in the provincial capital, also called Minya, was torched this week and the flames consumed everything inside.

"A neighbor called me and said the store was on fire. When I arrived, three extremists with knifes approached me menacingly when they realized I was the owner," recounted Naguib. His father and brother pleaded with the men to spare him. Luckily, he said, someone shouted that a Christian boy was filming the proceedings using his cell phone, so the crowd rushed toward the boy shouting "Nusrani, Nusrani," the Koranic word for Christians which has become a derogatory way of referring to them in today's Egypt.

Naguib ran up a nearby building where he has an apartment and locked himself in. After waiting there for a while, he left the apartment, ran up to the roof and jumped to the next door building, then exited at a safe distance from the crowd.

Two Christians have been killed since Wednesday, including a taxi driver who strayed into a protest by Morsi supporters in Alexandria and another man who was shot to death by Islamists in the southern province of Sohag, according to security officials, who spoke on condition of anonymity because they weren't authorized to release the information.

A total of 888 people have been killed nationwide since Wednesday's dismantling of two encampments of Morsi supporters in Cairo, with 79 of those deaths occurring on Saturday.

Meanwhile, the Egyptian government has begun deliberations on whether to ban the Brotherhood, a long-outlawed organization that swept to power in the country's first democratic elections a year ago.

Such a ban -- which authorities say would be implemented over the group's use of violence -- would be a repeat of the decades-long power struggle between the state and the Brotherhood.

The Brotherhood faces increasing public criticism over the ongoing violence in Egypt. Sheik Ahmed el-Tayeb, the powerful head of Al-Azhar mosque, Sunni Islam's main seat of learning, issued an audio statement asking Brotherhood members to stop the violence.

"The scenes of violence will not grant you any rights and the bloodshed nor chaos spreading across the country will give you no legitimacy," el-Tayeb said.

The Associated Press contributed to this report.