The head of Egypt’s army vowed to not back down in the face of violence, as a deadly crackdown on the Muslim Brotherhood showed the first signs of wearing down Islamists.

Gen. Abdel-Fatah el-Sissi said Sunday that the army would not stand by in the face of violence after hundreds have been killed in recent days in political unrest.

“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.

At the same time, an anti-coup alliance reportedly canceled a planned protest in Cairo, following a large troop buildup in the area and sweeping raids on Brotherhood Islamists around the country.

The group, including the Brotherhood, according to al-Jazeera, said it had canceled a march from Roxi Square to Heliopolis in Cairo after spotting military snipers stationed along the route of a planned march.

“Several marches in Cairo have been cancelled for security reasons,” Yasmine Adel, a spokeswoman with the Anti-Coup Coalition, told AFP.

Other marches on the Supreme Constitutional Court were still due to go ahead, as troops beefed up their presence around the building. Pictures posted to Twitter Sunday evening showed hundreds of people gathered in Minya, Suez and Fayoum.

El-Sissi led the July 3 ouster of president Mohammed Morsi. His comments came during his first appearance since a deadly crackdown Wednesday on two encampments of Morsi supporters that left hundreds dead.

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

“There is room for everyone in Egypt,” he said.

Earlier in the day, authorities carried out sweeping raids on the Brotherhood, detaining mid-level officials and field operatives in several cities, according to security officials and group statements.

In Assiut, 320 kilometers (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.

In the ancient southern city of Luxor, more than 20 Brotherhood senior officials were detained, officials said.

The officials spoke on condition of anonymity, as they were not authorized to speak publicly to journalists.

Under the banner of an anti-coup alliance, the Muslim Brotherhood earlier said it would hold a demonstration in front of the Supreme Constitutional Court later Sunday. Rallies were also planned across the country by supporters of ousted president Mohammed Morsi.

Armored vehicles and troops were deployed to the building in southern Cairo, leading to security concerns.

More than 800 people have been killed nationwide since Wednesday’s dismantling of two encampments of Morsi supporters in Cairo — an act that sparked fierce clashes.

The violence has brought growing international isolation for the country’s interim leadership.

The European Union said Sunday it would “urgently review” its relations with Egypt over the violence.

The presidents of the European Commission and the European Council, Jose Manuel Barroso and Herman Van Rompuy, said Sunday in a rare joint foreign-policy statement that it was the responsibility of the army and the interim government to end the violence.

They said calls for democracy and fundamental rights “cannot be disregarded, much less washed away in blood,” adding that “the violence and the killings of these last days cannot be justified nor condoned.”

EU foreign ministers were expected to hold an emergency meeting on Egypt this week. The bloc is a major source of aid and business for Egypt.

Egypt remained tense Sunday after security forces stormed a Cairo mosque a day earlier and the ousted president’s Muslim Brotherhood remained poised to hold further street protests despite a possible outlawing of the group.

Cairo said it had 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.

In a sign of lingering violence Sunday, troops exchanged gunfire with men shooting from a minaret of the al-Fath mosque on Ramses Square, where hundreds of supporters of Mohammed Morsi had fled overnight after violent clashes killed 173 people.

The evacuation was prompted by fears that the Brotherhood again planned to set up a sit-in, security officials said, similar to those that were broken up Wednesday in assaults that killed hundreds of people.

Simultaneously, police arrested the brother of al-Qaeda chief Ayman al-Zawahri, who, officials said, planned to bring in armed groups to provide support to those holed up inside the mosque.

Mohammed al-Zawahri, a Morsi ally, is the leader of the ultraconservative Jihadi Salafi group, which espouses al-Qaeda’s hard-line ideology. He was detained at a checkpoint in Giza, the city across the Nile from Cairo, the official said.

The official spoke on condition of anonymity, as he wasn’t authorized to brief journalists about the arrest.

For more than a month since the July 3 military overthrow of Morsi, Brotherhood members and supporters have attacked and torched scores of police stations and churches in retaliation. Shops and houses of Christians have also been targeted.

Such attacks spurred widespread public anger against the Brotherhood, giving the military-backed government popular backing to step up its campaign against the Islamist group. It reminded people of a decade-long Islamist insurgency against Mubarak’s rule in the 1990s, which only strengthened security agencies and ended with thousands of Islamic fundamentalists in prisons.

The unrest in Egypt has raised international concerns over the country’s stability and prompted UN Secretary General Ban Ki-moon to condemn, in a statement on Saturday, both “violent protests” in reference to Brotherhood’s rallies and the authorities’ “excessive use of force.”

On Wednesday, riot police, military helicopters, snipers and bulldozers broke up two sit-in protests in Cairo by Morsi supporters, leaving more than 600 people dead and thousands injured. That sparked days of violence that killed 173 people and injured 1,330 people on Friday alone, when the Brotherhood called for protests during a “Day of Rage,” Cabinet spokesman Sherif Shawki said.

Among those who died Friday was Ammar Badie, a son of the Brotherhood’s spiritual leader Mohammed Badie, the group’s political arm said in a statement.

Prime Minister Hazem el-Beblawi, who leads the military-backed government, later told journalists that authorities had no choice but to use force in the wake of recent violence.

The Muslim Brotherhood, founded in 1928, came to power a year ago when Morsi was elected in the country’s first free presidential elections. The election came after the overthrow of autocrat Hosni Mubarak in a popular uprising in 2011.

The fundamentalist group has been banned for most of its 85-year history and repeatedly subjected to crackdowns under Mubarak’s rule. While sometimes tolerated, with its leaders allowed to be part of the political process, members regularly faced long bouts of imprisonment and arbitrary detentions.

Disbanding the group, experts say, would mean allowing security forces to have a zero-tolerance policy in dealing with its street protests, as well as going after its funding sources. That could be a serious blow to the Brotherhood, though it likely wouldn’t mean an end to a group that existed underground for decades

The possible banning comes amid calls by pro-military political forces to brand the Brotherhood a “terrorist organization.”

“We are calling for declaring the Brotherhood a terrorist group,” said Mohammed Abdel-Aziz, one of the leaders of the Tamarod youth movement that had organized mass rallies calling for Morsi’s ouster.

The military-backed government has declared a state of emergency and imposed a dusk-to-dawn curfew since Wednesday, empowering army troops to act as a law enforcement force. Top Brotherhood leaders, including Morsi, remain held on a variety of charges, including inciting violence.

Since Morsi was deposed in the popularly backed military coup, the Brotherhood has stepped up its confrontation with the new leadership, rallying thousands of supporters in sit-ins and vowing not to leave until Morsi is reinstated.

After security forces broke up the protest camps, Islamist supporters stormed and torched churches and police stations. In response, the interim government authorized Egypt’s security forces to use deadly force against those attacking vital government institutions.

On Saturday, Egypt’s Interior Ministry said in a statement that a total of 1,004 Brotherhood members had been detained in raids across the country and that weapons, bombs and ammunition were confiscated from the detainees.

Several foreigners were also rounded up, including Sudanese, Pakistanis and Syrians, the Interior Ministry said.

Morsi himself has been held incommunicado since his ouster. Top Brotherhood leaders, including Khairat el-Shater, were detained last month.