Egypt's Muslim Brotherhood calls for fresh protests as crackdown's death toll hits 525

Updated at 10:42 a.m. ET

CAIRO Angry supporters of Egypt's ousted president stormed and torched Thursday two buildings housing the local government in Giza, the city next to Cairo that is home to the famed pyramids.

Associated Press reporters saw the buildings — a two-story colonial style villa and a four-story administrative building — set ablaze on Thursday.

The Giza government offices are located on the Pyramids Road on the west bank of the River Nile.

State TV blamed supporters of ousted President Mohammed Morsi for the fire. Its footage shows both structures burning with firefighters evacuating employees from the larger building.

Morsi's Muslim Brotherhood has called for fresh protests on Thursday, raising the specter of renewed violence. However, there were no reports of any large gatherings by early afternoon.

CBS News correspondent Charlie D'Agata reported on "CBS This Morning" Thursday from Cairo that the Brotherhood called Wednesday's violence no less than a massacre. On Thursday, they said their fight is not over, vowed to bring down what they called the "military coup" and said they remained committed to peaceful demonstrations.

On Martha's Vineyard in Massachusetts, where President Obama is vacationing, Mr. Obama announced that upcoming military exercises with U.S. and Egyptian forces would be canceledin light of Wednesday's crackdown.

"The Untied States strongly condemns the steps that have been taken by Egypt's interim government and security forces," Mr. Obama told reporters.

Also Thursday, Egyptian authorities significantly raised the death toll from Wednesday's clashes, saying more than 500 people died and laying bare the extent of the violence that swept much of the country and prompted the government to declare a nationwide state of emergency and a nighttime curfew.

The death toll, which stood at 525, according to the latest Health Ministry figures, makes Wednesday by far the deadliest day since the 2011 popular uprising that toppled longtime ruler and autocrat Hosni Mubarak — a grim milestone that does not bode well for the future of a nation roiled in turmoil and divisions for the past 2 1/2 years.

Health Ministry spokesman Khaled el-Khateeb put the number of the injured on Wednesday at 3,717.

The Brotherhood put the death toll at a staggering 2,600 and the injured at around 10,000 - figures that are extremely high in light of footage by regional and local TV networks, as well as The Associated Press.

CBS News producer Alex Ortiz, who was in the middle of the violence Wednesday as Egyptian forces laid siege to the protest camp outside the Rabbah al-Adawiya Mosque in Cairo's Nasr City district, reported most of the wounds he saw at a makeshift hospital inside the Rabaah camp were gunshots to the head and chest, consistent with reports of police automatic weapons and sniper fire being directed at the camp.

While the violence was not entirely one-sided - protesters pushed over a police car, killing four officers, and there were unconfirmed reports that some protesters were armed - the security forces used overwhelming force against them to clear the camps.

The Iman Mosque in Nasr City was packed with corpses, many of which were extremely burnt and blackened, Ortiz reports. The crowd there said they were victims of Wednesday's massive violence.

Inside, people placed blocks of ice on the shrouded dead, Ortiz reports. Others walked gingerly around the corpses upon the stained, wet carpet, spraying air-freshener in a futile attempt to counter the stench.

At least a hundred corpses were visible inside the mosque, Ortiz reports. Mourners slowly brought the bodies out in coffins and placed them into cars.

El-Khateeb said 202 of the 525 were killed in the Nasr City protest camp, but it was not immediately clear whether the bodies at the mosque were included in that figure. Another Health Ministry spokesman, Mohammed Fathallah, said he had no knowledge of the bodies at the el-Iman mosque.

"They accuse us of setting fire to ourselves. Then, they accuse us of torturing people and dumping their bodies. Now, they kill us and then blame us," screamed a woman in a head-to-toe black niqab.

Omar Houzien, a volunteer helping families search for their loved ones, said the bodies were brought in from the Medical Center at the sit-in camp site in the final hours of Wednesday's police sweep because of fears that they would be burned.

A list plastered on the wall listed 265 names of those said to have been killed in Wednesday's violence at the sit-in. Funerals for identified victims were expected to take place later on Thursday.

Meanwhile, a mass police funeral — with caskets draped in the white, red and black Egyptian flag — was held in Cairo for some of the 43 security troops killed in Wednesday's clashes.

Interior Minister Mohammed Ibrahim, who is in charge of the police, led the mourners. A police band played funerary music as a somber funeral procession moved with the coffins placed atop red fire engines.

Wednesday's violence started with riot police raiding and clearing out the two camps, sparking clashes there and elsewhere in the Egyptian capital and other cities.

Ortiz reports Cairo was eerily quiet Thursday morning. Indeed, the city of some 18 million people had only a fraction of its usually hectic traffic and many stores and government offices shuttered. Many people hunkered down at home for fear of more violence. Banks and the stock market were closed.

The latest events in Egypt drew widespread condemnation from the Muslim world and the West, including the United States, Egypt's main foreign backer for over 30 years.

Nobel Peace Prize winner Mohamed ElBaradei resigned later Wednesday as Egypt's interim vice president in protest — a blow to the new leadership's credibility with the pro-reform movement.

Interim Prime Minister Hazem el-Beblawi said in a televised address to the nation that it was a "difficult day" and that he regretted the bloodshed but offered no apologies for moving against Morsi's supporters, saying they were given ample warnings to leave and he had tried foreign mediation efforts.

Several prominent Brotherhood figures were detained as police swept through the two sit-in sites, scores of other Islamists were taken into custody, and the future of the once-banned movement was uncertain.

Backed by helicopters, police fired tear gas and used armored bulldozers to plow into the barricades at the two protest camps on opposite ends of Cairo. Morsi's supporters had been camped out since before he was ousted by a July 3 coup that followed days of mass protests by millions of Egyptians demanding that he step down.