Tensions are rising in Egypt, where mass demonstrations are planned Sunday calling for President Mohamed Morsi to step down.
Organizers of the protest claimed Saturday that more than 22 million people have signed their petition demanding the Islamist leader resign, asserting that the tally is a reflection of how much the public has turned against his rule.
Late Saturday, thousands gathered in Cairo's Tahrir Square ahead of the planned demonstrations.
At least seven people have been reported killed, including an American citizen, and hundreds injured in clashes between pro and anti-Morsi supporters this past week.
Earlier Saturday, U.S. President Barack Obama said the U.S. is looking at Egypt's escalating political unrest with concern.
During a joint news conference in Pretoria with South Africa's President Jacob Zuma, Obama said the U.S. supports peaceful methods to bring about change in Egypt.
"I think every party has to denounce violence," he said. "We'd like to see the opposition and President Morsi engaged in a more constructive conversation around how they move their country forward because nobody is benefiting from the current stalemate that exists there."
Authorities say three people were killed Friday, including Andrew Pochter, a young American student who was stabbed to death while photographing protests in Alexandria.
In a statement, Pochter's family said he loved the region's culture and had a summer job teaching English to school children in Alexandria.
Egypt's opposition has been accusing Morsi and his Muslim Brotherhood movement of trying to undermine secular rights.
Activists are planning a massive anti-government rally in Cairo's Tahrir Square on Sunday, which is the anniversary of Morsi's ascent to the presidency last year.
Meanwhile, at least eight members of Egypt's upper house of parliament [Shura Council] announced they were resigning on Saturday, in protest of Morsi.