Apparently there was a spontaneous element as well.

After the hearing, Rep. Dutch Ruppersberger, D-Maryland, blamed confusion over two seemingly different versions of the consulate violence — was it caused by a protest or by terrorists?
He said there were essentially two threads of violence: one caused by the protest, which was chaotic, and a second that was orchestrated by terrorists, which was highly coordinated.
There were “two different types of situations at play,” Ruppersberger said, explaining that in the hours and days after the attack, it was naturally difficult to clearly discern what happened.
Intelligence evolves, he said, and new information comes out when agents obtain it. He downplayed the idea that there was something untoward going on.

The former CIA chief has said there was a stream of intelligence from multiple sources, including video at the scene, that indicated the group was behind the attack, according to an official with knowledge of the situation.
Meanwhile, separate intelligence indicated the violence at the consulate was inspired by protests in Egypt over an ostensibly anti-Islam film that was privately produced in the United States. The movie, “Innocence of Muslims,” portrayed the Prophet Mohammed as a womanizing buffoon.
There were 20 intelligence reports that indicated that anger about the film may be to blame, the official said.
The CIA eventually disproved those reports, but not before Petraeus’ initial briefing to Congress the day after the attack when he discussed who might be behind the attack and what prompted it. During that briefing, he raised Ansar al Sharia’s possible connection as well as outrage about the film, the official said.
Earlier an official said that Petraeus’ aim in testifying was to clear up “a lot of misrepresentations of what he told Congress initially.”
Petraeus testified that he developed unclassified talking points in the days after the attack but he had no direct involvement in developing the ones used by Susan Rice, the U.S. ambassador to the United Nations, King said.
Rice has been under fire for suggesting the attack on the consulate was a spontaneous event spurred by a protest against the anti-Muslim film.