The United States dispatched two Navy destroyers and an elite group of Marines to Libya on Wednesday, as officials began investigating the cause of a fiery mob attack on the U.S. Consulate in Benghazi that killed the ambassador and three other Americans.
Tuesday's stunning attack poses a daunting task for U.S. and Libyan investigators: searching for the culprits in a city rife with heavy weapons, multiple militias, armed Islamist groups and little police control.
Officials are trying to determine whether the rampage was a backlash to an anti-Islamic video with ties to Coptic Christians or a plot to coincide with the anniversary of Sept. 11.
The one-story villa that serves as the consulate was a burned-out wreck after the crowd armed with machine guns and rocket-propelled grenades rampaged through it. Slogans of "God is great" and "Mohammed is God's prophet" were scrawled across its scorched walls. Libyan civilians strolled freely in charred rooms with furniture and papers strewn everywhere.
President Barack Obama vowed in a Rose Garden address that the United States would "work with the Libyan government to bring to justice" those who killed Ambassador Chris Stevens, information manager Sean Smith and two other Americans who were not identified. Three other Americans were wounded.
Stevens was the first U.S. ambassador killed in the line of duty in 30 years.
"We reject all efforts to denigrate the religious beliefs of others, but there is absolutely no justification for this type of senseless violence. None," said Obama, who also ordered increased security at U.S. diplomatic posts abroad.
Republican Mitt Romney accused the Obama administration of showing weakness in the consulate killings, but the president retorted that his rival "seems to have a tendency to shoot first and aim later." Some in the GOP called Romney's remarks hasty.
The mob attack on Tuesday was initially presumed to have been a spontaneous act triggered by outrage over a movie called Innocence of Muslims that mocked Islam's prophet Mohammed that was produced in the United States and excerpted on YouTube. The amateurish video also drew protests in Cairo, where angry ultraconservatives climbed the U.S. Embassy's walls, tore down an American flag and replaced it with an Islamic banner.
But a U.S. counterterrorism official told the Associated Press that the Benghazi violence was too coordinated or professional to be spontaneous.
The FBI was sending evidence teams to Libya, a law enforcement official said.
Libya's new leadership — scrambling to preserve ties with Washington after U.S. help to overthrow former dictator Moammar Gadhafi — vowed to find those behind the attack. Interim President Mohammed el-Megarif apologized to the United States for what he called the "cowardly" assault, which also killed several Libyan security guards at the consulate in the eastern city.
Parliament speaker Omar al-Houmidan suggested the attack might have been planned, saying the mob "may have had foreign loyalties" — an apparent reference to international terrorists. "We are not sure. Everything is possible," he said.
A Libyan jihadist group, the Omar Abdel-Rahman Brigades, claimed responsibility for a bomb that went off outside the Benghazi consulate in June, causing no injuries.
The group, which also carried out several attacks on the International Red Cross in Libya, said at the time that the bomb was revenge for the killing of al-Qaida's No. 2, Abu Yahya al-Libi, in a U.S. drone strike in Pakistan.
About 50 U.S. Marines were sent to Libya to guard U.S. diplomatic facilities. The Marines are members of an elite group known as a Fleet Antiterrorism Security Team, or FAST, whose role is to respond on short notice to terrorism threats and to reinforce security at embassies.
The consulate attack illustrated the breakdown in security in Libya, where the government is still trying to establish authority months after Gadhafi's fall.
There also were indications that two distinct attacks took place — one on the consulate, then a second hours later early Wednesday on a nearby house to which the staff had been evacuated.
The crowd of several thousand that descended on the consulate was armed with machine guns and rocket-propelled grenades, said Wanis el-Sharef, the deputy interior minister of Libya's eastern region.
A small contingent of Libyan security protecting the facility fired in the air, trying to intimidate the mob. But faced with superior size and firepower, the Libyan security withdrew, el-Sharef said. Gunmen stormed the building, looted its contents and torched it, he said.
Details of how the Americans were killed were still unclear.
Stevens, 52, and a consulate staffer who had stayed behind in the building died in the initial attack, el-Sharef said. The rest of the staff successfully evacuated to a nearby building, preparing to move to Benghazi Airport after daybreak to fly to the capital of Tripoli, he said.
Hours after the storming of the consulate, a separate group of gunmen attacked the other building, opening fire on the more than 30 Americans and Libyans inside. Two more Americans were killed, he said.
Dr. Ziad Abu Zeid, who treated Stevens, told the Associated Press that he died of asphyxiation, apparently from smoke. In a sign of the chaos, Stevens was brought by Libyans to the Benghazi Medical Center with no other Americans, and no one at the facility knew who he was, Abu Zeid said.
He said he tried to revive Stevens for about 90 minutes "with no success."
The bloodshed stunned many Libyans, especially since Stevens was a popular envoy among different factions and politicians, including Islamists, and was seen as a supporter of their uprising against Gadhafi.
The violence in Libya raised worries that further protests could break out in the Muslim world.
In Cairo, some 200 Islamists staged a second day of protest outside the U.S. Embassy on Wednesday, but there were no more attempts to scale the embassy walls. After nightfall, the group dwindled and some protesters scuffled with police, who fired tear gas and dispersed them.
In a statement on his official Facebook page, Egypt's Islamist president, Mohammed Morsi, condemned the movie, saying the government was responsible for protecting diplomatic missions as well as the freedom of speech and peaceful protest.
He said authorities "will confront with full determination any irresponsible attempt to break the law."