"This is not acceptable to the Libyan people; this is not acceptable to our values," Prime Minister Mustafa Abushagur told CNN, referring to Tuesday's deadly assault on the U.S. consulate in Benghazi. "We are taking this very, very seriously."
The one suspect arrested and "three or four" being actively pursued are Libyans, Abushagur said, adding there are "suspicions that these people belong to some extremist group, but ... that is something we don't know."
The prime minister offered details on the case shortly after Libyan Deputy Interior Minister Wanis al-Sharif said that "some individuals" suspected in the case were in custody, according to state-run LANA news agency.
In response to the Benghazi attack, the United States deployed Marines to secure its interests in the region, as well as warships and drones to hunt for those responsible for killing the four American diplomatic staffers.
Neither Abushagur nor al-Sharif detailed the suspects' motives. Elsewhere around the world, however, a growing number of Muslims have taken to the streets to direct their outage at the United States over an obscure 14-minute film trailer that mocks Islam's prophet. It was posted in July on YouTube, but got more notice recently after Egyptian television aired segments and anti-Islam activists promoted it online.
Numerous questions surround the film, which includes cartoonish scenes of Mohammed as a womanizer, child molester and ruthless killer. The filmmaker was identified in a July 2011 casting call as Sam Bassiel and on the call sheet as Sam Bassil; the name was reported at first by news outlets as Sam Bacile.
By Thursday, as new details emerged, it was becoming apparent that Bacile was probably not the producer's real name. And two members of the film's production staff who spoke to CNN denied initial media reports that the filmmaker was an Israeli Jew.
Here's the latest on the violence and unrest around the region, the response and the implications:
Since Tuesday's deadly assault in Libya -- and a protest the same day at the U.S. Embassy in Cairo -- demonstrations, both small and large, have been reported in Israel, Gaza, Libya, Egypt, Yemen, Sudan, Tunisia, Morocco, Iraq, Iran and among Muslims in the Indian-controlled region of Kashmir. Security has been heightened at U.S. diplomatic missions worldwide.
While some protesters say they have not seen any of the online film, they were incensed by reports of its depiction of the Prophet Mohammed.
One of the largest protests Thursday took place outside the U.S. Embassy in Cairo. One photo from Cairo shows a chalk drawing on the ground of a Jewish star with the words in Arabic, "Remember your black day 11 September." Demonstrators threw rocks and Molotov cocktails as police tried to disperse them by firing tear gas canisters.
At least 13 protesters and six police officers were injured, Egyptian government officials said.
The instability in Egypt is a primary concern to U.S. President Barack Obama, who warned in an interview with Telemundo that it would be "a real big problem" if the leaders in Egypt failed to protect American interests there.
Another massive protest took place Thursday in Sanaa, Yemen, where demonstrators breached a security wall at the U.S. Embassy as several thousand people protested outside.
Violent clashes left 24 members of the security forces and three protesters injured, Yemen's Defense Ministry and witnesses said.
Protesters and witnesses said the three protesters had been hurt, one critically, when police fired on them as they tried to disperse the angry crowd.
Here are details about other protests:
-- In Tunisia and Morocco, protesters massed in front of U.S. embassies.
-- In Gaza City, Palestinians demonstrated outside U.N. headquarters, and about 200 Palestinians protested the film at the Palestine Legislative Council building. In one instance, Palestinian men burned a U.S. flag.
-- In Tel Aviv, Israel, about 50 people demonstrated in front of the U.S. Embassy.
-- In Sudan, the United States called on U.S. citizens Wednesday to stay away from the embassy in Khartoum, where protests were going on.
-- Iranians protested near the Swiss Embassy in Tehran on Thursday. Switzerland represents U.S. interests in Iran, since Washington and Tehran do not have diplomatic relations. Up to 500 people chanted "Death to America!" and called for death to the director of the movie, which was made in the United States. The demonstration ended peacefully after two hours.
The Islamic Propagation Coordination Council, meanwhile, has issued a statement calling for rallies across Iran on Friday "to protest Zionist-U.S. plots against Muslim and Islamic values," the state-run IRNA news agency reported.
-- In Iraq, specifically in the predominantly Shiite area of eastern Baghdad known as Sadr City, hundreds of protesters hit the streets to protest the film. They chanted, "America is the enemy of the people," with some burning an American flag and others putting one on the ground and stomping on it. Other followers of radical cleric Muqtada al-Sadr also protested in the provinces of Najaf and Karbala.
So far, the violence has not spread to Afghanistan, where there is a high potential for outrage to erupt into destabilizing chaos. Obama and his Afghan counterpart, Hamid Karzai, have expressed their commitment to prevent that from happening.
FBI reaches out to anti-Islam filmmaker
As questions swirl about the film at the center of the ongoing protests, U.S. officials stepped up their criticism of the video and began pursuing the elusive filmmaker who allegedly made the video.
"To us, to me personally, this video is disgusting and reprehensible," Secretary of State Hillary Clinton said Thursday. "It appears to have a deeply cynical purpose, to denigrate a great religion and to provoke rage. But as I said yesterday, there is no justification, none at all, to responding to this video with violence. We condemn the violence that has resulted in the strongest terms. And we greatly appreciate that many Muslims in the United States and around the world have spoken out on this issue."
The FBI has spoken to the filmmaker within the past 24 hours, a federal law enforcement officer told CNN on Thursday. Federal officials consider that man to be Nakoula Basseley Nakoula, who was convicted in 2009 of bank fraud.
Short clips of the film were available on YouTube and included cartoonish scenes of Mohammed as a womanizer, child molester and ruthless killer.
Many Muslims find any depiction of Mohammed to be offensive -- a Danish newspaper's publication in 2005 of Mohammed caricatures triggered riots -- and derogatory depictions of the prophet are considered by some to be worse.
The Afghan government has ordered an indefinite block of YouTube to prevent people there from watching the clips and staging violent protests. YouTube has already restricted access to the video.
Response to ambassador's killing
Sources tracking militant Islamist groups in eastern Libya say Tuesday night's deadly attack was most likely carried out by a pro-al Qaeda group. Obama has vowed that "justice will be done."
U.S. warships, carrying guided missiles, are on their way to the coast of Libya, and unmanned drones are being sent to help search for the killers.
A group of Marines called a Fleet Antiterrorism Security Team was deployed to Libya to help secure U.S. facilities, two U.S. officials said. About 50 Marines arrived in the country Wednesday, officials said.
U.S. political fallout
The events have shifted the U.S. presidential race to a focus on foreign policy, with Republican nominee Mitt Romney repeatedly criticizing the responses by Obama and his administration.
At a Virginia rally Thursday, Romney said, "As we watch the world today, sometimes it seems that we're at the mercy of events instead of shaping events, and a strong America is essential to shape events."
Obama, in an interview Wednesday with CBS, took aim at Romney's sharply negative criticism that seemed to inject politics during a time of still-developing international crisis.
"Gov. Romney seems to have a tendency to shoot first and aim later," Obama said, adding, "It's important for you to make sure that the statements that you make are backed up by the facts and that you've thought through the ramifications before you make them."
Stay with NewsChannel 3 for the latest.