Egyptian authorities have arrested a key Muslim Brotherhood leader, continuing a crackdown against the group following the military's ouster of Islamist president Mohamed Morsi.
Security forces detained Essam el-Erian, the deputy leader of the Brotherhood's political wing , at his hideout Wednesday in the eastern suburb of New Cairo.
Hours later police stormed the main building of al-Azhar University - the country's top institution for Islamic teachings - after protesting students besieged and attacked the offices of the university's chief administrator.
Students at al-Azhar have been demonstrating for weeks in support of Mr. Morsi, whom the army toppled in July after mass protests against his rule.
El-Erian had been in hiding since the July coup and was one of the few top Brotherhood officials who had remained free.
Hundreds of Brotherhood leaders, including Mr. Morsi, have been arrested since July and charged with inciting violence. The deposed leader's supporters have carried out mass protests demanding he be reinstated.
Some of the demonstrations have turned violent. More than 1,000 people, mostly Islamists, have been killed in the clashes and crackdown.
Mr. Morsi, in detention at an undisclosed military location, is accused of inciting violence that caused the deaths of other protesters in June. His trial is set to open November 4.
El-Erian is also a defendant in the Morsi trial.
His arrest came just hours after three judges presiding over the trial of 35 Brotherhood members stepped down after security agencies refused to let the defendants attend the courtroom sessions.
The move - a sharp pushback from within the establishment over the conduct of the trial - means a new set of judges will be assigned and the proceedings will have to start over.