A state of emergency has been declared across Egypt, as security forces and supporters of deposed president Mohamed Morsi continue to clash around the country.
The announcement on Wednesday came amid a deadly crackdown by security forces on two pro-Morsi protest camps in Cairo.
The health ministry said at least 149 people had been killed in clashes around the country, but some members of Morsi's Muslim Brotherhood said the death toll was much higher.
The state of emergency began at 4pm local time (14:00 GMT) and will last for a month, the presidency said in a statement.
The exceptional measures were taken as "the security and order of the nation face danger due to deliberate sabotage, and attacks on public and private buildings and the loss of life by extremist groups," the presidency said.
Interim president Adly Mansour "has tasked the armed forces, in cooperation with the police, to take all necessary measures to maintain security and order and to protect public and private property and the lives of citizens".
A curfew has also been imposed in Cairo and nine other provinces, starting from 9pm local time (19:00 GMT) until 6am (04:00 GMT).
Interim vice president Mohamed ElBaradei resigned following Wednesday's violence, saying in a letter to the country's leadership that there were peaceful options for ending the political crisis.
Al Jazeera's Sherine Tadros, reporting from Cairo, said the military has now been given "a mandate by cabinet to play an active role in the crackdown, if the situation escalates, and we have seen that the situation has escalated."
"It is a very worrying situation, and the state of emergency only serves to highlight the very precarious situation," she said.
The Interior Ministry said 543 pro-Morsi supporters were arrested nationwide, in incidents related to dispersing the sit-ins of Rabaa and Nahda. The arrests were made for possession of arms including automatic weapons, and large amounts of ammunition.
Police took full control of the Rabaa al-Adawiya camp on Wednesday afternoon, the state news agency reported.
Al Jazeera's Jane Ferguson, reporting from Nasr City, said smaller groups had been congregating in squares and streets after the protest camp was cleared out.
"Just because they're leaving Rabaa Square doesn't mean that they're leaving protests altogether," she said.
Earlier in the day, there were scenes of panic and carnage in the square as security forces moved in to disperse protesters.
Ammar Beltagi, the son of Mohammad Beltagi, the head of the Muslim Brotherhood's Freedom and Justice party, told Al Jazeera his 17-year-old sister, Asmaa, was shot and killed in the Rabaa al-Adawiya sit-in in Nasr City.
Two journalists were also killed while covering the violence. Mick Deane, a cameraman for the UK-based Sky News channel, and Habiba Abd Elaziz, a reporter for the UAE-based Xpress newspaper, died from gunshot wounds.
Live footage from Cairo on Wednesday morning showed smoke engulfing Nahda Square, the smaller of the two sit-ins based in Giza, amid reports of tear gas and birdshots being used on supporters of the deposed president.
By mid-morning, the Interior Ministry said security forces had "total control" over Nahda Square, and that "police forces had managed to remove most of the tents" in the area. Security forces had blocked all access to the protest camp.
In an afternoon press conference, the cabinet media adviser thanked the security forces for "exercising self-control and high-level professionalism in dispersing the sit-ins," and held the Muslim Brotherhood responsible for "escalation and violence".
Witnesses said that after firing tear gas into the Rabaa al-Adawiya sit-in, pandemonium struck among the thousands of protesters who had set up camp there soon after Morsi was ousted by the army on July 3.
Protesters have camped in Cairo demanding the reinstatement of Morsi, who was country's first democratically elected president and his Freedom and Justice Party was the largest political group in the now dissolved parliament.
Clashes quickly erupted between protesters and security forces on one side of the camp, with automatic fire reverberating across the square. It was not immediately clear who was shooting.
Television footage showed the injured being carried to a makeshift medical centre as well as police dragging away protesters, who had defied numerous ultimatums by the army-installed authorities to end their demonstrations.
Police barred journalists not already in the camp from entering.
In response to the security operation, the Muslim Brotherhood urged Egyptians to take to the streets across the country to "stop a massacre".