BREAKING NEWS UPDATE:
Egypt's top military commander says the army is now in full control of the country and President Mohammed Morsi has been replaced by the chief justice of the constitutional court as the interim head of state.
He made the announcements in a Wednesday night speech -- the latest twists in an all-out power struggle inside Egypt that Morsi's national security adviser is describing as a military coup.
Gen. Abdel-Fattah el-Sissi said Morsi has failed to meet the demands of Egypt's people and the country's constitution has been temporarily suspended.
Fireworks erupted in Tahrir Square after the announcement was made.
Earlier story below:
Before the announcement, Egyptian troops, including commandos in full combat gear, were deployed across much of Cairo, including at key facilities, on bridges over the Nile River and at major intersections.
The military has vowed to defend its people "against any terrorist, radical or fool.” Top military officials and opposition leaders held talks for most of the day and a statement was expected at the conclusion.
"For the sake of Egypt and for historical accuracy, let’s call what is happening by its real name: Military coup," the Morsi adviser, Essam al-Haddad, said on his Facebook page.
An aide told Reuters that Morsi had spent the day working at a presidential office in a compound of the Republican Guard in Cairo, but it was unclear if he would be able to return later to his palace.
Witnesses told Reuters that the army was erecting barbed wire and barriers around the compound, and moving in vehicles and troops to prevent supporters from getting to his palace.
A travel ban was put on Morsi and the head of his Muslim Brotherhood, Mohammed Badie, as well as Badie's deputy Khairat el-Shater, officials told the Associated Press.
The Freedom and Justice Party (FJP) -- the political wing of the Muslim Brotherhood -- has denied that Morsi was placed under house arrest.
Minutes before the military’s deadline for Morsi to resolve the nation’s political crisis passed Wednesday afternoon, the embattled leader called for "national reconciliation," but vowed he would never step down.
Millions were in the main squares of major cities nationwide, demanding Morsi's removal, in the fourth day of the biggest anti-government rallies the country has seen, surpassing even those in the uprising that ousted against his autocratic predecessor Hosni Mubarak. Critics say Morsi has set the nation on a path toward Islamic rule.
"The presidency renews its own roadmap and invites all national forces for dialogue," Morsi said in a statement on his Facebook page, adding that his vision is to hold a coalition government that will run upcoming parliamentary elections. Morsi also said he was looking to "form an independent committee for constitutional amendments to be presented to the coming parliament."
He described electoral legitimacy as the only safeguard against violence and instability.
Khaled Daoud, spokesman of the main opposition National Salvation Front, which pro-reform leader Mohamed ElBaradei leads, said that ElBaradei, Sheik Ahmed el-Tayeb, grand imam of Al-Azhar mosque, and Pope Tawadros II, patriarch of Egypt's Coptic Christian minority, were part of the meeting with military leaders.
Political sources told Reuters that two members of a rebel youth group that is leading the anti-Morsi protests and members of the hardline Muslim fundamentalist al-Nour Party also were attending.
State news agency MENA said the group will jointly announce a short period of transitional rule to be followed by presidential and parliamentary elections, according to Reuters.
A Defense Ministry official said Gen. Abdel-Fattah el-Sissi also held an emergency meeting earlier in the day with his top commanders, hours before the deadline expired. The official, who gave no further details, spoke Wednesday on condition of anonymity because he was not authorized to brief the media, the Associated Press reports.
The army also asked the FJP to meet with el-Sissi, but the invite was rejected.
"We have a president and that is it," Waleed al-Haddad, a senior leader of the party, told Reuters.
The state-run Al-Ahram newspaper -- which also seemed to be following a military line -- reported that the military had placed several leaders of Morsi's Muslim Brotherhood under surveillance.
Before the deadline expired at 5 p.m. local time (11 a.m. ET), employees at Egypt's state TV station said military officers were present in the newsroom monitoring its output, but not interfering with their work.
The military also beefed up the presence of troops inside the building, the employees told the Associated Press, though they were not visible outside. Even before the crisis, a small army contingent usually guards the state TV headquarters.
Earlier Wednesday, Egypt’s military vowed to defend the country’s people.
"We swear to God that we will sacrifice even our blood for Egypt and its people, to defend them against any terrorist, radical or fool,” read a post on the official Facebook page of the Supreme Council of the Armed Forces.
A military source told Reuters that the statement — issued after Morsi appeared on state TV late Tuesday to once again reject an ultimatum from Sissi that he share power with opponents or face military action — reiterated that the armed forces would not abandon their demands.
In his emotional 46-minute speech, Morsi vowed not to step down and pledged to defend his legitimacy with his life in the face of three days of massive street demonstrations calling for his ouster. The Islamist leader accused loyalists of his ousted autocratic predecessor Hosni Mubarak of exploiting the wave of protests to topple his regime and thwart democracy.
"There is no substitute for legitimacy," said Morsi, at times angrily raising his voice, thrusting his fist in the air and pounding the podium. He warned that electoral and constitutional legitimacy "is the only guarantee against violence."
The statements showed that Morsi and his Muslim Brotherhood are prepared to run the risk of challenging the army. It also entrenches the lines of confrontation between his Islamist supporters and Egyptians angry over what they see as his efforts to impose control through the Brotherhood and his failures to deal with the country's multiple problems.
At the main pro-Morsi rally in Cairo, thousands of his Islamist supporters chanted, "Wake up el-Sissi, Morsi is my president."
"We will not bring back the military rule," they chanted outside the Rabia al-Adawiya Mosque. "Will not happen, will not happen," they shouted.
After the army's deadline passed, a military helicopter circled over the crowds in Tahrir Square, which was transformed into a sea of furiously waving Egyptian flags. "Leave, leave," they chanted to Morsi, electrified as they waited to hear of an army move. After nightfall, fireworks went off and green lasers flashed over the crowd.
The current showdown follows a night of deadly clashes in Cairo and elsewhere in the country that left at least 23 people dead, most in a single incident near the main Cairo University campus. The latest deaths take to 39 the number of people killed since Sunday in violence between opponents and supporters of Morsi, who took office in June last year as Egypt's first freely elected leader.
The bloodshed, coupled with Morsi's defiant speeches, contributed the sense that both sides are ready to fight to the end.
Mahmoud Badr, spokesman for the youth movement behind the latest wave of protests, called on anti-Morsi protesters to demonstrate Wednesday outside three presidential palaces as well as the Cairo headquarters of the Republican Guard, an army branch tasked with protecting the president, his family and presidential palaces. Morsi is thought to have been working at the Republican Guard headquarters since the start of the protests.
Badr also called on the army to place Morsi under arrest for his alleged incitement to civil war.
"Today is the day of decisiveness," Badr said at a news conference.
On Tuesday, millions of jubilant, chanting Morsi opponents again filled Tahrir Square, as well as avenues adjacent to two presidential palaces in the capital, and main squares in cities nationwide.
The president's supporters also moved out in increased marches in Cairo and other cities, and stepped up warnings that it will take bloodshed to dislodge him.
On Monday, the military gave Morsi the ultimatum to meet the protesters' demands within 48 hours. If not, the generals' plan would suspend the Islamist-backed constitution, dissolve the Islamist-dominated legislature and set up an interim administration headed by the country's chief justice, the state news agency reported.
The leaking of the military's so-called political "road map" appeared aimed at adding pressure on Morsi by showing the public and the international community that the military has a plan that does not involve a coup.
Fearing that Washington's most important Arab ally would descend into chaos, U.S. officials said they are urging Morsi to take immediate steps to address opposition grievances, telling the protesters to remain peaceful and reminding the army that a coup could have consequences for the massive American military aid package it receives. The officials spoke on condition of anonymity because they were not authorized to speak publicly.
At the U.S. State Department media briefing Wednesday, spokeswoman Jen Psaki restated the administration's priority on the democratic process.
"It's never been about one individual," she told reporters. "It's been about hearing and allowing the voices of the Egyptian people to be heard."
Pentagon Spokesman George Little says there has been no change in terms of the U.S. military prepositioning assets in and around Egypt in the event they are called upon to assist the U.S. embassy in Cairo.
The Associated Press contributed to this report.