CAIRO (CNN) -- Protesters marching on Egypt's presidential palace Tuesday night broke through barbed wire keeping them away from the building and tossed chairs and rocks at retreating police in the nation's latest episode of unrest.
Police lobbed tear gas in return.
No injuries were immediately reported but the Health Ministry said at least 50 ambulances had been dispatched to locations around Cairo, including 20 to the presidential palace. Hospitals were placed on high alert in anticipation of injured protesters, the ministry said.
President Mohadmed Morsy was out of the palace meeting with government leaders to discuss the upcoming referendum on the draft of a new constitution, his office said.
The protest caps a day of silent protest by media organizations opposing the country's new draft constitution and an edict Morsy issued nearly two weeks ago to expand his powers.
Article 48 of the draft constitution ties media freedom to the framework of society and national security, which many Egyptian journalists see as vague terminology.
State news agency Egynews confirmed the media strike, sourcing the head of Egypt's Journalists' Syndicate. State-owned outlets remained open, said Gamal Fahmi.
There was one exception, when journalists at state-owned news website Al-Ahram joined in the protest, Fahmi said.
Four privately owned television stations will go off the air Wednesday in solidarity, according to a statement by broadcaster ONTV, which is participating in the strike.
The protests come as Egyptians are counting down to a public referendum on the draft constitution to be held in less than two weeks.
Some newspapers disappeared from news stands Tuesday. Others printed the same protest picture of the press symbolically behind bars with the headline, "No to Dictatorship."
The English-language online daily Egypt Independent grayed out its home page and posted a message on a black slate, stating that it "objects to continued restrictions on media liberties."
The paper believes the government has intimidated Egyptian journalists by hitting them with investigations, said deputy editor Amira Ahmed.
State TV journalists Hala Fahmy and Bothaina Kamel are being investigated for "professional errors" committed on air, according to state news agency MENA and have been suspended pending investigation results.
Morsy decreed nearly two weeks ago that all decisions he has made since taking office are exempt from judicial review, saying it was necessary to block judges trying to thwart gains made in the revolution.
Egypt's judiciary contains many holdover loyalists from the government of deposed autocratic President Hosni Mubarak. Some judges had threatened to shut down the Islamist dominated Constituent Assembly tasked with drafting a new constitution.
A court is to hear lawsuits Wednesday calling for the annulment of Morsy's decree, according to a lawyer representing organizations challenging its validity. Islamist lawyers are trying to block the suits, Ahmed Hossam said.
About 1,000 judges from around the country agreed Sunday that they would not supervise the December 15 national referendum on the constitution, members of the Egyptian Judges Club said. The club's unanimous decision means court officials who would normally sort out any irregularities in voting will abstain from the process in protest.
But on Monday, members of the Egypt's Supreme Judicial Council -- the nation's highest judicial body -- agreed to supervise the referendum, Judge Abdel Rahman Behloul said. This group's members had initially criticized Morsy's edict, but they softened their stance after a meeting with him last week.
"We have been conducting a survey and, despite the position of the Judges Club to boycott the review of the referendum, we have received feedback from many prominent judges who are willing to oversee the vote," Behloul said. An estimated 11,000 judges will be needed to oversee the vote.
Al Zind, from the judges club, said 90% of judges are refusing to participate "but there are also Muslim Brotherhood judges" and others supportive of Morsy's stance. He claimed the Supreme Judicial Council "has no real power, they are heads of courts that deal with administrative matters."
Boisterous protests have filled streets of Cairo and other cities for over a week, at times turning violent, as the opposition accused Morsy of usurping dictatorial powers with his edict.
In the heat of the public outrage, the Constituent Assembly, its members strongly allied with Morsy, rushed to complete the draft and hand it off to the president, who put it to a public referendum.
He has promised his controversial edict will dissolve as soon as the referendum is over, but the rush to finish the draft has only fanned the flames of protest from all sides of his opposition among the judiciary, liberals, Christians, leftists and now the press.
Some members of the assembly walked out and were replaced by more Islamists, tilting the balance even farther in Morsy's favor and fueling accusations of a power grab.
The document that voters will consider has itself become a source of significant controversy.
Prime Minister Hesham Kandil insisted Monday that opposition views -- including that there would be protections for women and to prevent Egypt from becoming a theocracy -- were taken into consideration when the final draft was pushed through Friday.
"It is impossible to have a perfect text that everybody agreed to," the prime minister said. "... I think there is a majority consensus to move forward with the referendum. In two weeks, we'll find out what Egyptians think of this constitution."
Egypt effectively has been without a constitution since the early 2011 popular uprising that led to Mubarak's ouster.
Journalist Sarah Sirgany in Cairo and CNN's Ben Brumfield in Atlanta contributed to this report.
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