(CBS/AP) U.S. officials believe that an attack on a U.S. Consulate in Libya resulting in the death of an American ambassador may have been planned and not solely the actions of a spontaneous mob demonstrating against an online video ridiculing Islam's Prophet Muhammad.
"This was a coordinated attack, more of a commando-style event," House Intelligence Committee Chairman Mike Rogers, R-Mich., told CBS News Capitol Hill producer Jill Jackson. "It had both coordinated fire -- direct fire and indirect fire. There appeared to be military maneuvers approaching the facility."
U.S. Ambassador to Libya Christopher Stevens and three other Americans died in the attack on the U.S. Consulate in the eastern Libyan city of Benghazi Tuesday.
A U.S. source told CBS News investigative producer Pat Milton that authorities were "leaning" toward the theory that al Qaeda planned the attack and that the protest seems to have been a fortuitous coincidence for the militants. The fact that some of the attackers were armed with rockets and grenades is one of the factors leading to that initial conclusion.
Rogers told Jackson there was a "high likelihood" that the attack had an affiliation with "al Qaeda elements in Libya."
Wanis al-Sharef, a Libyan Interior Ministry official in Benghazi, said there had been threats that Islamic militants might try to take revenge for the death of al Qaeda's No. 2 commander Abu Yahya al-Libi, who was
killed in a U.S. drone strike in Pakistan in June, and he said the U.S. consulate should have been better protected.
Confirming al-Libi's death for the first time in a video posted online Monday, al Qaeda chief Ayman Al-Zawahri called on Muslims in al-Libi's native Libya to take revenge for his death.
Some authorities are looking at the possibility that the attack may have been planned to coincide with the anniversary of the Sept. 11 terror attacks and this week's killing in Yemen of Saeed al-Shihri, who was second in command of al Qaeda in the Arabian Peninsula, Milton reports.
U.S. officials believe the militants were using the demonstration against the video as a cover to get into the consulate and then take as much revenge as they could on Americans, CBS News national security correspondent David Martin reports.
"Absolutely it's a terrorist attack," Rogers told Jackson. "This was not done by the Libyan government. It was done by an external group we believe has at least extremist ties, maybe al Qaeda ties, and the style and the signature of the attack clearly would be something that we have seen before and would be in line with something al Qaeda would do."
Military officials told CBS News an anti-terrorism team of U.S. Marines was being deployed to Libya to help secure U.S. interests in the country following the attack. The State Department said, however, that no Americans were remaining at the facility in Benghazi. State officials would not confirm how many Americans were evacuated, or to where.
Al-Sharef said Stevens, 52, and other officials were moved to a second building - deemed safer - at the consulate compound after the initial wave of the attack. According to al-Sharef, members of the Libyan security team seem to have indicated to the attackers the building to which the American officials had been relocated, and that building then came under attack.
Stevens was the first U.S. ambassador to be killed in the line of duty since 1979. A Libyan doctor who said he treated Stevens told The Associated Press Wednesday that the diplomat died of severe asphyxiation and that he tried for 90 minutes to revive him.
