Zyad el-Elaimy was among millions who rallied to overthrow Hosni Mubarak in 2011, but four years later he is visiting some of them who are now in jail while the ousted strongman edges closer to release from prison.

The jubilation that had marked Mubarak's toppling -- a key event of the 2011 Arab Spring --  is dead, and activists say an even more autocratic regime now rules the most populous Arab country.

A bomb in Cairo wounded four policemen and a civilian Friday, officials said.

It was the second in the capital in as many days, after an explosion wounded a police officer late Thursday outside the Al-Qubba presidential palace.

An Egyptian conservation group said Friday it will sue the antiquities minister over a "botched" repair of the mask of King Tutankhamun that left a crust of dried glue on the priceless relic.

The golden funerary mask, seen Friday by AFP at the Egyptian Museum, showed the sticky aftermath of what appears to have been overzealous use of glue to fix the mask's beard in place.

A young woman was killed in Egypt Friday as Islamist supporters of ousted president Mohamed Morsi protested ahead of the fourth anniversary of the 2011 uprising that toppled his predecessor, Hosni Mubarak.

The 18-year-old was killed by birdshot in the Mediterranean city of Alexandria and her mother wounded during a demonstration after Friday prayers, a security official said.

Two sons of Egypt's ousted leader Hosni Mubarak seen as symbols of his era's corruption were freed from prison on Friday pending a graft retrial, state media reported.

Alaa and Gamal Mubarak left jail early Friday after a court ordered their release because they had served the maximum pretrial detention, the state-owned Al-Ahram newspaper reported on its website

A police officer was injured when a small bomb exploded outside the presidential palace in Cairo on Thursday, police sources said.

An unknown assailant on a motorbike threw the bomb in front of the main entrance of the Al-Qubba palace before fleeing, the sources said.

Egypt's public prosecutor Thursday ordered the release of 100 students arrested in a crackdown on protests since late 2013, ahead of the fourth anniversary of a popular uprising.

The students, who have not been formally charged, will be set free out of "concern for their academic future", the prosecutor's office said in a statement.

An Egyptian court on Thursday ordered the release of ousted president Hosni Mubarak's two sons pending their retrial on corruption charges, a judicial official said.

Their lawyer Farid al-Deeb told AFP Alaa and Gamal Mubarak were free to leave prison after the court order because they had served the maximum pretrial detention period.

A leading Islamic organization has called on the United Nations to make "contempt of religions" illegal and urged the West to protect Muslim communities following the attack on French magazine Charlie Hebdo.

The Qatar-based International Union of Muslim Scholars, headed by  influential preacher Yusuf al-Qaradawi, appealed to Muslims to continue peaceful protests against images of the Prophet Mohammed but "not to resort to any violence".

President Abdel Fattah al-Sisi acknowledged Tuesday that police committed rights abuses after the overthrow of his Islamist predecessor, but said they were expected given the "exceptional" security threats faced by Egypt.

A crackdown overseen by Sisi against supporters of his predecessor Mohamed Morsi has left hundreds dead since the then army chief toppled the Islamist in July 2013.