Egyptians took to the streets Friday to mark the anniversary of the 2011 revolution that ended the 30-year rule of Egyptian President Hosni Mubarak.
The U.S. Embassy in Cairo said clashes among various political parties and groups were unlikely but warned there may be a heavy security presence throughout the country.
"However, the high level of emotion surrounding the anniversary could lead to violence should extreme elements seek confrontation," the warning read.
Political tensions in 2012 ran high as Egyptian President Mohamed Morsi took office. He hails from the Muslim Brotherhood, leading to concerns about the role of Islam in the new Egyptian government.
The Muslim Brotherhood, on its official website, reported that its press office in Cairo was set on fire Thursday by demonstrators.
Demonstrations were reported in major Egyptian cities following Friday prayers. Police responded with tear gas when protesters in Cairo threw Molotov cocktails.
The Egyptian Independent newspaper, meanwhile, adds that the headquarters for the Brotherhood's Freedom and Justice Party was raided by demonstrators in Ismailia, a city on the Suez Canal.