Here's a look at what you need to know about the September 11, 2012 attack on the U.S. mission in Benghazi, Libya.
Facts: September 11, 2012 - The U.S. mission in Benghazi, Libya, is attacked and burned. An attack later that night involves mortar and rocket fire against a U.S. diplomatic annex in the city.
U.S. Ambassador Christopher Stevens and three other U.S. nationals are killed in the attack.
More than 30 Americans are evacuated.
Initially, the attack was thought to be perpetrated by an angry mob responding to a video made in the U.S. which mocked Islam and the Prophet Mohammed, but it is later determined to be a terrorist attack.
September 11-12, 2012 Attack Timeline as released by the Pentagon: September 11: (Events listed in local Benghazi time) 9:42 pm - Armed men begin their assault on the U.S. mission.
9:59 pm - A surveillance drone is directed to fly over the U.S. compound, but it is unarmed.
10:32 pm - The Office of the Secretary Defense and the Joint Staff are notified of the attack by the National Military Command Center at the Pentagon. "The information is quickly passed to Secretary Panetta and General Dempsey."
11 pm - Secretary Panetta and Chairman of the Joint Chiefs of Staff Gen. Martin Dempsey meet with President Barack Obama at the White House where they discuss the unfolding situation and how to respond. The meeting had been previously scheduled.
11:10 pm - The surveillance drone arrives over the Benghazi facility.
11:30 pm - All surviving U.S. personnel are evacuated from the mission. U.S. Ambassador Chris Stevens and State Department computer expert Sean Smith are killed in the initial assault.
September 12: Midnight to 2 am - Secretary Panetta and other senior leaders discuss possible options for further violence if it were to break out. Panetta gives verbal orders for Marine anti-terrorist teams from Rota, Spain, to prepare to deploy to Tripoli and Benghazi. Panetta also orders a special operations force team training in Croatia and an additional special operations force team in the United States to prepare to deploy to a staging base in southern Italy.
1:30 am - A six-man security team from the U.S. Embassy in Tripoli arrives in Benghazi.
2:39 am to 2:53 am - The National Military Command Center gives formal authorization for the deployment of the two special operations force teams from Croatia and the United States.
5:15 am - Attackers launch assault on a second U.S. facility in Benghazi. Two former U.S. Navy SEALs acting as security contractors are killed. They are identified as Tyrone Woods and Glen Doherty.
6:05 am - A C-17 aircraft in Germany is told to prepare to deploy to Libya to evacuate the mission personnel.
7:40 am - The first wave of Americans are evacuated to Tripoli via airplane.
10 am - A second group, including those killed in the attack, are flown to Tripoli.
2:15 pm - The C-17 departs from Germany for the flight to Tripoli.
7:17 pm - The C-17 leaves Tripoli with the American mission personnel and the bodies of Stevens, Smith, Woods and Doherty.
7:57 pm - The U.S. special operations force team based in Croatia arrives at a staging base in Italy.
8:56 pm - One of the Marine anti-terrorist teams from Spain arrives in Tripoli.
9:28 pm - The U.S.-based special operations force team arrives at its staging base in Italy.
Timeline: September 11, 2012 - Initial reports claim a mob of angry protestors gather outside the U.S. temporary mission in Benghazi, Libya. Protestors reportedly storm the building, and Ambassador Stevens dies of smoke inhalation as does IT expert Sean Smith. Two security personnel, former U.S. Navy Seals Glen Doherty and Tyrone Woods, are killed in a subsequent attack after helping to evacuate those at the mission to a US diplomatic annex.
September 11, 2012 - Republican presidential candidate Mitt Romney releases a statement at about 10:30 p.m. ET, "I'm outraged by the attacks on American diplomatic missions in Libya and Egypt and by the death of an American mission worker in Benghazi. It's disgraceful that the Obama administration's first response was not to condemn the attacks on our diplomatic missions, but to sympathize with those who waged the attacks." This was in response to the U.S. Embassy in Cairo releasing a statement denouncing the film, "Innocence of Muslims," that had led to the protests. Later it emerges that the statement preceded the protests.