US president Obama U.S. President Barack Obama strongly condemned Wednesday the killing of J. Christopher Stevens, Washington's ambassador to Libya, in a mob attack at a U.S. Consulate, fueled by anger over a film mocking Islam. Obama called the attack "outrageous," and confirmed that three other Americans were killed by rockets fired at the U.S. Consulate in the eastern city of Benghazi. "Chris was a courageous and exemplary representative of the United States," Obama said. An "angry crowd" marched on the U.S. compound Tuesday, furious about an American-produced online film considered offensive to Muslims, said Libya's Deputy Interior Minister Wanis al-Sharif . The U.S. mission in Egypt was also attacked Tuesday in response to the film depicting the prophet Mohammed as a child molester, womanizer and ruthless killer. Stevens was the first U.S. ambassador to be killed in an attack since 1979. Libya's Prime Minister Abdurrahim el-Keib apologized "to the American people and the government, and also to the rest of the world" for the "cowardly criminal act." U.S. Secretary of State Hillary Clinton identified a second victim as Sean Smith, a Foreign Service information management officer who was a 10-year veteran of the State Department, a husband and a father of two. The two other victims have not been named. Consulate security staff opened fire after they heard gunfire outside the mission, Al-Sharif said. "This led to more anger and this is when the consulate was stormed," he said, suggesting that people loyal to deposed dictator Moammar Gadhafi were aiming to create chaos among the protesters. "Criminals managed to get in and they burned and ransacked the consulate," he said. The U.S. mission is very badly damaged and was being looted on Wednesday, said a contractor working at the mission, who asked not to be named for security reasons. He said he saw the bodies of all four Americans on the street Wednesday morning.