Arrests have been made in connection with the attack on the U.S. consulate in Benghazi, Libya, which left four people, including U.S. Ambassador Chris Stevens, dead, according to a report from Libya’s state-controlled news agency.

Libya’s Deputy Minister of Interior Wanis Al-Sharif also said in a statement that "the investigation is ongoing and will reveal either whether those individuals are involved [in the killings] or innocent."

Reuters quoted Sharif as saying “four men are in custody, and we are interrogating them, because they are suspected of helping instigate the events at the U.S. consulate."

Sharif provided no further details.

"We have made a big advance [in the investigation]," Libya's Prime Minister Mustafa Abu Shagur told the Agence France Presse news agency. "We have some names and some photographs. Arrests have been made and more are under way as we speak."

The FBI is also in Libya investigating the attack. A government official speaking on the condition of anonymity told CBS News the bureau will send investigators to Germany to interview U.S. Consulate personnel who were evacuated there.

CBS reports officials already have a prime suspect in the attack: A radical Islamic group called Ansar al Sharia. The name means "Supporters of Islamic law" and U.S. officials describe it as an offshoot of al Qaeda.

Al-Sharif said the attacks probably were timed to mark the 9/11 anniversary and that the militants used civilians protesting an anti-Islam film as cover. Infiltrators within the security forces may have tipped off militants to the safe house location, he said.

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