Egypt's Mansour Calls for Probe after the Death of 42 Islamists during Demo

Egypt's interim leader Adly Mansour launched an investigation into violence in Cairo that killed 42 people on Monday during an Islamist demonstration calling for the army to restore Mohammed Morsi as president.

"The president of the republic forms a judicial commission to investigate the events at the Republican Guard" headquarters, state television reported.

Forty-two loyalists of Morsi were killed on Monday while demonstrating against last week's military coup, triggering an Islamist uprising call and dashing the army's hopes for an interim civilian administration.

The Muslim Brotherhood, which has led demonstrations against the overthrow of Islamist president Morsi last Wednesday, said its supporters were "massacred" when police and troops fired on them during dawn prayers outside an elite army headquarters in Cairo.

The military blamed "terrorists" while witnesses, including Brotherhood supporters at the scene, told Agence France Presse that the armed forces fired only tear gas and warning shots and that "thugs" in civilian clothes had carried out the deadly shooting.

Prominent liberal leader Mohammed ElBaradei called for an independent inquiry into the bloodshed. Turkey strongly condemned the killings.

The conservative Islamist Al-Nur party, which won almost a quarter of votes in a 2011 parliamentary election and had given its support to the army's overthrow of Morsi, said it was pulling out of talks on a new government in response to the "massacre".

The bloodshed happened outside the headquarters of the elite Republican Guard, whom the Brotherhood accuses of betraying Morsi.

Brotherhood supporters hurled stones at the security forces who responded with tear gas, as firefighters battled to extinguish a blaze that raged in an apartment block, an AFP correspondent reported.

"Morsi supporters were praying while the police and army fired live rounds and tear gas at them," the Brotherhood said.

A senior medical official told AFP at least 42 people were killed and 322 wounded.

The army said "armed terrorists" tried to storm the base, leaving one security officer dead and six critically wounded.

The Brotherhood's political arm, the Freedom and Justice Party, called for "an uprising by the great people of Egypt against those trying to steal their revolution with tanks".

It urged "the international community and international groups and all the free people of the world to intervene to stop further massacres... and prevent a new Syria in the Arab world".

A security official said prosecutors later ordered the closure of the FJP's Cairo headquarters after police discovered weapons that they alleged were to be used in attacks against Morsi opponents.

ElBaradei, a Nobel Peace laureate, called for an independent investigation.

"Violence begets violence and should be strongly condemned. Independent Investigation a must. Peaceful transition is only way," the former U.N. nuclear watchdog chief said on his official Twitter account.

Morsi's single year of turbulent rule was marked by accusations he failed the 2011 revolution that ousted autocratic president Hosni Mubarak by concentrating power in Islamist hands and letting the economy nosedive.