Fireworks light up the sky as Hundreds of thousands of Egyptians celebrate after Egytptian Defense Minister Abdel Fattah al-Sisi's speech announcing The Egyptian army toppling Islamist President Mohamed Morsi in Egypt's landmark Tahrir square on July 3, 2013 in Cairo, Egypt. (Getty Images)
CAIRO (NBC) -- An Egyptian constitutional court judge appointed by Hosni Mubarak - the strongman leader ousted by the Arab Spring uprising - was sworn in as interim president on Thursday after the military overthrew the country's first democratically elected head of state.
Adly Mansour, chairman of the Supreme Constitutional Court, pledged to look after the interests of "the great people of Egypt," promised fresh elections, and urged the revolutionaries who helped topple Islamist President Mohammed Morsi to stay in Cairo's Tahrir Square.
A spokesman for the Brotherhood confirmed that Morsi was under house arrest at the Republican Guard Club. Most members of presidential team have also been placed under house arrest.
On Wednesday, armored vehicles, tanks and troops were deployed throughout Cairo, as the army seized the headquarters of the state television and the state-run newspaper.
The army has stressed it had no interest in power and also said they wanted to see early elections but it was unclear when they would occur. The country's constitution, which opponents of Morsi claimed was rewritten to favor his Muslim Brotherhood movement, was suspended on Wednesday.
Mansour, 68, was first appointed to the constitutional court by Mubarak, who was forced out in 2011 after some three decades in power. Earlier this year, Morsi picked him to become the chief justice.
As he took the presidential oath, Mansour said he would respect the rule of law and "look after the interests of the people," according to a live translation by BBC News.
He said he had received an "order" to become interim president from "the great people of Egypt."
Mansour said Egypt should stop producing "tyrants" and worship only God, not "any president or any statutes."
He also said he hoped the protesters who helped topple Morsi would remain in Tahrir Square and continue "flying the flag of this revolution."
"We look forward to hold presidential and parliamentary elections based on a genuine people's will," Mansour said.
He said Egypt's judiciary had had to put up with attempted attacks on their independence under Morsi, but had "stood on the side of the people."
Ahead of being sworn in as interim president, Mansour took the oath of office as head of the constitutional court Thursday. He was appointed so recently by Morsi that this had not yet happened.
He studied law at Cairo University, graduating in 1967. He also studied in Paris and was a legal adviser to the Saudi Arabian Ministry of Trade from 1983 to 1990, according to Muftah.org. He became a judge in 1984. Mansour became deputy head of the constitutional court in 1992, the BBC said.
Mohammed Hamed El Gamal, the former head of the State Council judicial body, in a statement to Al Shabab, an offshoot of state-run newspaper Al Ahram, said Mansour was a "fair man" with allegiances only to "the constitution and the law."
"I am certain that he will respect the will of the Egyptian people and legal and constitutional legitimacy ... He will be cooperative, understanding and execute the will of the people as he has always done," Gamal said, according to a translation on Muftah.org.
The Brotherhood was left to cry foul after their victory in last year's elections -- deemed to be free and fair -- was overturned by the military.
A "new era of repression and tyranny, of an impending authoritarian police state" had begun, the Brotherhood's website said, with TV channels shut down, arrests of politicians and "many citizens killed as they demonstrated peacefully."
Mohamed Saad Katatni, the head of the Brotherhood's Freedom and Justice Party, was arrested. His son Muaaz Saad Katatni denounced his father's arrest. "Those who claim to defend freedoms and democracy, invited my father for dialogue in the afternoon ... then arrested him in the evening," he said, according to the website, adding "Welcome to the new era of freedoms!"
Mohamed Beltagy, member of the Freedom and Justice Party executive bureau, was quoted on the Brotherhood's website as saying that they had tried to stay in power and negotiate a solution not in "defense of any particular person or group, but to defend the will of the people which is ... not expressed in mutual crowd-massing but using the tools of democracy which we accepted and they rejected."
He said Morsi's followers had not resorted to violence but "our leaders and youths were killed, our offices - and even our homes - stormed, ransacked, burned and totally destroyed - not to mention the insults and obscenities we had to suffer."
"As electoral and constitutional legitimacy is rejected, a certain viewpoint is imposed on all, and guardianship is enforced over the people against their clearly expressed will," Beltagy added.
In a statement, President Barack Obama said the United States supported "a set of core principles, including opposition to violence, protection of universal human rights, and reform that meets the legitimate aspirations of the people."
He added: "We are deeply concerned by the decision of the Egyptian Armed Forces to remove President Morsi and suspend the Egyptian constitution. I now call on the Egyptian military to move quickly and responsibly to return full authority back to a democratically elected civilian government as soon as possible through an inclusive and transparent process, and to avoid any arbitrary arrests of President Morsi and his supporters."
Early Thursday, it remained unclear whether the U.S. government would define the military's decision to oust Morsi as a coup. This could affect the $1.5 billion in aid given to Egypt annually.
U.S. law bans military or financial assistance "to the government of any country whose duly elected head of government is deposed by military coup or decree."
Obama said in his statement that he had "directed the relevant departments and agencies to review the implications under U.S. law for our assistance to the government of Egypt."
"No transition to democracy comes without difficulty, but in the end it must stay true to the will of the people," he added. "An honest, capable and representative government is what ordinary Egyptians seek and what they deserve."
The army insisted it had not carried out a coup, but had acted on the will of the people to clear the way for a new leadership.
A statement from Morsi's office's Twitter account quoted the deposed president as saying the military's measures "represent a full coup categorically rejected by all the free men of our nation."