Arrest made in connection with deadly assault on U.S. consulate in Libya

As an anti-Islam video continued to spawn protests and violence around the region, Libya's prime minister said Thursday at least one person has been arrested -- and others were in authorities' sights -- tied to the killings of a U.S. ambassador and three others this week.

"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.