An American staff member of the U.S. consulate in the eastern Libyan city of Benghazi has died following fierce clashes at the compound, two Libyan security sources said on Wednesday.

"One American staff member has died and a number have been injured in the clashes," Abdel-Monem Al-Hurr, spokesman for Libya's Supreme Security Committee, said, adding that he did not know the exact number of injured.

Armed gunmen attacked the compound on Tuesday evening, clashing with Libyan security forces before the latter withdrew as they came under heavy fire. Reuters reporters on the scene could see looters raiding the compound, walking off with desks, chairs and washing machines.

According to a Libyan Interior Ministry official, the armed men stormed the U.S. consulate and set it ablaze after a protest against a film deemed insulting to Islam's prophet, Mohammed, which was reportedly produced in America.

Witnesses say Tuesday's attack left much of the consulate burned.

According to a Wall Street Journal report, the director of the movie, called "Innocence of Muslims," is an Israel-American, 52-year-old Sam Bacile, who wanted to show "Islam as a cancer." Mr Bacile claims that 100 Jewish donors funded the movie to the tune of $5 million, the newspaper reported.  

The United States condemned the attack and said efforts are underway with the help of Libyan authorities to secure the facility.

State Department spokesperson Victoria Nuland said in a statement: "We can confirm that our office in Benghazi, Libya has been attacked by a group of militants. We are working with the Libyans now to secure the compound. We condemn in strongest terms this attack on our diplomatic mission."

U.S. Secretary of State Hilary Clinton said in a statement: “I condemn in the strongest terms the attack on our mission in Benghazi today. As we work to secure our personnel and facilities, we have confirmed that one of our State Department officers was killed. We are heartbroken by this terrible loss. Our thoughts and prayers are with his family and those who have suffered in this attack.

“This evening, I called Libyan President Magariaf to coordinate additional support to protect Americans in Libya. President Magariaf expressed his condemnation and condolences and pledged his government’s full cooperation,” read Clinton’s statement.

Islamists scale U.S. embassy in Cairo

The attack in Libya came hours after ultraconservative Islamist demonstrators in Egypt climbed the walls of the U.S. Embassy in Cairo to protest a film being produced by Egyptian Coptic Christians living in the U.S.

Egyptian soldiers had been sent to the area in central Cairo to prevent several hundred demonstrators who gathered outside the embassy from storming it.

Several protesters climbed up onto the walls of the embassy, tore down the U.S. flag, and raised a black flag, before they were removed by security reinforcements who were rushed to the area.

In a statement earlier Tuesday, the embassy condemned what it called "continuing efforts by misguided individuals to hurt the religious feelings of Muslims."

In Washington, U.S. State Department spokeswoman Victoria Nuland said the embassy in Cairo was "working with Egyptian authorities to restore order and get the situation back under control."

She also urged observers not to draw conclusions about U.S.-Egyptian relations based on the incident, pointing to progress made in engaging with civil society. Nuland said the U.S. hopes protests will remain peaceful and it will continue to support Egypt's democratic transition.

Permanent security barriers on the streets around the embassy had recently been removed, in a long-delayed implementation of a court decision won by local traders.