Protesters angered over an amateur American-made film that mocks Islam's Prophet Muhammad fired gunshots and set fire to the U.S. consulate in the eastern Libyan city of Benghazi Tuesday, killing a State Department officer.

In Egypt, protesters scaled the fortified walls of the U.S. embassy in Cairo and replaced an American flag with an Islamic banner. The demonstrators there – mainly ultraconservative Islamists – are continuing their protest action through the early hours Wednesday.

U.S. Secretary of State Hillary Clinton confirmed that a U.S. official was killed in the Benghazi attack, which she condemned “in the strongest terms.”

Clinton said some have sought to justify “this vicious behavior” as a response to inflammatory material posted on the Internet, and noted that the U.S. deplores any intentional effort to denigrate the religious beliefs of others.

The mobs were sparked by outrage over the film that U.S. media said was produced by an Israeli-American and financed by expatriate members of Egypt's Coptic Christian minority group. Excerpts from the film in English and Arabic were posted on YouTube.

The video is being promoted by controversial Christian Pastor Terry Jones, who said Tuesday the film was not designed to attack Muslims but to show the “destructive ideology of Islam.”

Jones inspired deadly riots in Afghanistan in 2010 and 2011 by threatening to set fire to copies of the Quran and then burning one in his church.

The U.S. Embassy in Cairo released a statement Tuesday saying it condemned “the continuing efforts by misguided individuals to hurt the religious feelings of Muslims.”

The protests coincide with the 11th anniversary of the September 11th terrorist attacks in the United States.