Egyptian police fired tear gas Sunday in an attempt to free a guard from rioting detainees, suffocating at least 36 as the country's military leader vowed to tolerate no more violence after days of clashes that killed nearly 900 people.

The deaths of the prisoners, captured during the fierce fighting in recent days around Cairo's Ramses Square, came as Gen. Abdel-Fatah el-Sissi also called for the inclusion of Islamists in the government.

Meanwhile, security forces detained members of the Islamist group Muslim Brotherhood in raids aimed at stopping more planned rallies supporting ousted President Mohammed Morsi — which the military-backed government says fuels the violent unrest.

The suspects killed were part of a prison truck convoy of some 600 detainees heading to Abu Zaabal prison in northern Egypt, security officials told The Associated Press. Detainees in one of the trucks rioted and managed to capture a police officer inside, the officials said.

Security forces fired tear gas into the truck in hopes of freeing the badly beaten officer, the officials said. The officials said those killed died from suffocating on the gas. 

However, the officials' version of event contradicted reports about the incident carried by state media. The official website of Egyptian state television reported that the deaths took place after security forces clashed with militants near the prison and detainees came under fire while trying to escape. The official MENA state news agency also said the trucks came under attack from gunmen.

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Supporters of President Mohammed Morsi carry a wounded man during clashes with security forces in Ramses Square, downtown Cairo on Friday. (Hassan Ammar/Associated Press)

State media also said all those killed and the gunmen belonged to the Muslim Brotherhood, the organization that Morsi hails from. The officials who spoke to AP said some of the detainees belonged to the Brotherhood, while others didn't.

The violence adds to the ever-rising death toll in days of unrest. On Saturday alone, clashes between Morsi supporters and police killed 79 people, according to a government tally released Sunday and carried by MENA. That raised the death toll for four days of unrest across the country to nearly 900 people killed. Some 70 police officers were killed in clashes with protesters or retaliatory attacks during the same period, according to the Interior Ministry.

Cabinet holds emergency meeting

Security forces arrested hundreds of Muslim Brotherhood members early Sunday morning in raids on their homes in different cities, aimed at disrupting planned rallies to support Morsi. The cabinet also held an emergency meeting to discuss potentially banning the group, a long-outlawed organization that swept to power in the country's first democratic elections a year ago.

In his first appearance since the violence began, el-Sissi spoke at length in an hour-long speech about the motives behind ousting Morsi. The general said the Islamist president exploited democracy to monopolize power. He again said the military's action "protected Egyptians from civil war," despite the ongoing violence on the streets.

"We will not stand by silently watching the destruction of the country and the people or the torching the nation and terrorizing the citizens," el-Sissi said in a speech aired on state television. "I am not threatening anyone. ... If the goal is to destroy the country and the people, no!"

El-Sissi also said Islamists must be included in the country's politics moving forward. A military timetable calls for the nation's constitution to be amended and for presidential and parliamentary elections to be held in 2014.

In Egypt's second-largest city Alexandria, the Brotherhood said on its official website that security forces stormed houses of 34 officials and former lawmakers, but only arrested seven people. Among those targeted was Medhat el-Haddad, the brother of top Morsi's aide Essam el-Haddad.

In Assiut, 320 kilometers 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.

Brotherhood told to stop violence

The Brotherhood faces increasing public criticism and blame 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.

El-Tayeb supported the military coup that ousted Morsi.

Nearly two weeks of international diplomacy by the EU, U.S. and Arab nations failed to broker a peaceful end to the standoff.

Egypt also lost one of the few doves in the country's military-backed administration as Mohamed ElBaradei, who resigned as vice-president in protest of the use of force against Morsi's supporters, left Cairo for Vienna on Sunday. ElBaradei, who won the Nobel Peace Prize in 2005 as head of the UN's atomic energy agency, declined to speak to journalists as he left Egypt, where pro-military news outlets have become increasingly hostile toward him.