Egyptian authorities have detained senior Muslim Brotherhood leader Essam el-Arian, the latest arrest in a government crackdown against the Islamist movement, an Interior Ministry source said.
Arian, the deputy leader of the Brotherhood-linked Freedom and Justice party, was taken into custody from a residence in New Cairo where he had been in hiding.
"Yes, he's been arrested and details will soon be released," the source told the Reuters news agency on Wednesday.
The state news agency MENA said Arian was arrested in New Cairo but gave no further details.
Local media circulated a photograph of what they described as the moment he was arrested, showing a smiling Arian standing next to a bed with two packed duffle bags.
Many Brotherhood leaders have been detained and charged with inciting violence since the army, prompted by mass protests, deposed president Mohamed Morsi on July 3.
On Wednesday afternoon, students at al-Azhar university protested el-Arian's arrest.
The students besieged offices, hurled chairs and smashed windows, according to a report by Reuters news agency.
"Sisi is a dog. Down, down with the lord of the army," one protester scribbled, refering to army chief General Abdel Fattah al-Sisi, who led the overthrow of Morsi.
One police officer yelled: "Arrest anyone you see. Bring me those kids. If you see anyone just arrest them right away."
Mustafa el-Agrawi, al-Azhar's legal adviser, told the ONTV private channel that the students besieged the administrative building, locking up the university chief and several other administrators.
Ahmed Hosni, deputy head of al-Azhar, said the students stormed the offices, trashed documents and computers to "sabotage and destroy the university".
The head of al-Azhar university had called on the police to enter campus grounds to "protect souls and properties", according to an interior ministry statement.
Egyptian security forces fired tear gas at the protestors and arrested 20 protesters, according to two security sources.