Protesters in Egypt clashed with riot police and soldiers outside the US Embassy in Cairo for the second night in a row late Wednesday as anger over an anti-Islam film continued to foment.
Police fired tear gas and rubber bullets outside the embassy and several people were injured in the clashes, including 14 soldiers and policemen.
Video showed demonstrators throwing stones and setting small fires.
The clashes lasted until after dawn Thursday, as security forces pushed protesters away from the embassy and toward Tahrir Square, Al Arabiya reported.
Egyptian news outlet Al-Ahram reported that about 200 people attended the protest, with several firebombs hurled at security forces.
Many of the protesters were reportedly members of the Ultras, a militant soccer fan club that has played large roles in protests in the past and has emerged as a potent political force in the country.
Many of the demonstrators were unbearded, the outlet reported, a marked difference from the day before, when protests were seemingly dominated by hard-line Islamists.
On Tuesday, an angry mob of some 2,000 stormed the embassy grounds, tearing down the American flag and replacing it with a pro-Islam banner. Hours later, gunmen in Libya stormed a consulate building in Benghazi, killing the American ambassador in the country, Chris Stevens, and three other staff members.
Security at US embassies in the Arab world was ramped up after the protests.
Officials originally believed the Libya attack to be linked to the film produced by a mysterious American showing the Islamic prophet Muhammad as a feckless skirt-chaser who abused children, though they are now investigating the possibility that it was a planned al-Qaeda attack.
Clashes were also reported in Tunisia on Wednesday, as several hundred people protested outside the US Embassy in Tunis.
US President Barack Obama called the presidents of Libya and Egypt Thursday morning and urged them to continue working with the US to ensure the safety of diplomatic personnel.
Egyptian President Mohammed Morsi promised Egypt “would honor its obligation to ensure the safety of American personnel,” the White House said.
Obama told Morsi that while “he rejects efforts to denigrate Islam… there is never any justification for violence against innocents.”