CAIRO — Thousands of Muslim Brotherhood supporters have taken to the streets in several Cairo neighborhoods and elsewhere in Egypt in defiance of the military-imposed state of emergency.
The protesters poured out of the mosques after Friday prayers, responding to the group's call for a "Day of Rage" following the deaths of 638 people Wednesday when riot police backed by armored vehicles, snipers and bulldozers smashed the two sit-ins in Cairo where ousted President Mohammed Morsi's supporters had been camped out for six weeks to demand his reinstatement.
The government has authorized the use of deadly force against protesters targeting police and state institutions while the international community has urged both sides in Egypt to show restraint and end the turmoil engulfing the nation.

The Interior Ministry, which is in charge of national security, said in a statement that the new measures come after an angry crowd stormed the buildings in Giza, the city next to Cairo that is home to the Pyramids.

"The ministry has given instruction to all forces to use live ammunition to confront any assaults on institutions or the forces," the statement read.

Attackers set fire to churches and police stations across the country on Wednesday after security forces assaulted two Cairo sit-ins where thousands of supporters of ousted President Mohammed Morsi were camped out. Officials say the death toll is now 638, mostly Morsi supporters, and 4,200 injured.

Meanwhile, Egypt's military-backed government pledged in a statement to confront "terrorist actions and sabotage" allegedly carried out by members of Morsi's Muslim Brotherhood group.

"The Cabinet expressed its determination to confront the terrorist actions and sabotage by elements of the Muslim Brotherhood organization," it said. "These actions are carried out as part of criminal plan that clearly aims at toppling down the state."

On Wednesday, the government declared a nationwide state of emergency and a nighttime curfew.

Associated Press reporters witnessed the burning buildings in Giza — a two-story colonial-style villa and a four-story administrative building. The offices are located on the Pyramids Road on the west bank of the River Nile.

State TV blamed Morsi supporters for the fire and broadcast footage showing both structures burning as firemen evacuated employees from the larger building.

The Brotherhood website Ikhwanweb said thousands marched through Giza but were attacked by pro-military "militias." It did not say how the government buildings were set on fire.

In the coastal city of Alexandria, witnesses and a security official said, Morsi supporters stabbed a taxi driver to death for hanging a picture of Defense Minister Gen. Abdel-Fatah el-Sissi, the leader of the July 3 coup.

"The driver was caught in middle of a protest by the Muslim Brotherhood chanting against the military. He argued with them to watch out, they pulled him out (of his car) and stabbed him," said Mohammed el-Mashali, a reporter for the al-Fagr weekly who said he witnessed the killing.

The official spoke on condition of anonymity because he was not authorized to speak to the press.

Tamarod, the youth movement that organized mass rallies calling for Morsi's ouster, said citizens should set up neighborhood watch groups to protect government and private property.

Meanwhile, successive attacks on Coptic Christian churches continued for a second day, according to Egypt's official news agency and human rights advocates.

Egypt's MENA agency said Morsi supporters set fire to the Prince Tadros church in the province of Fayoum, nearly 50 miles (80 kilometers) southwest of Cairo.

Ishaq Ibrahim from The Egyptian Initiative for Personal Rights says his group has documented as many as 39 incidents of violence against churches, monasteries, Coptic schools and shops in different parts of the country on Wednesday.