(CBS/AP) BENGHAZI, Libya - The attack that killed four Americans in Libya, including the U.S. ambassador, was an organized two-part operation by heavily armed militants that included a precisely timed raid on a supposedly secret safe house just as Libyan and U.S. security forces were arriving to rescue evacuated consulate staff, a senior Libyan security official said on Thursday.
Libyan authorities have made four arrests in the investigation into the attack on the U.S. consulate in Benghazi in which the U.S. ambassador and three embassy staff were killed, the deputy interior minister said on Thursday, according to Reuters.
"Four men are in custody and we are interrogating them because they are suspected of helping instigate the events at the U.S. consulate," Wanis el-Sharef, eastern Libya's deputy interior minister, told Reuters.
He said others were being closely monitored by police to see whether they are linked to a group. He refused to elaborate.
The FBI is also in Libya investigating the attack. A government official speaking on the condition of anonymity told CBS News the FBI is planning to send investigators to Germany to interview Libyan U.S. Consulate personnel who were evacuated there.
El-Sharef said the attacks Tuesday night were suspected to have been timed to mark the 9/11 anniversary and that the militants used civilians protesting an anti-Islam film as cover for their action. Infiltrators within the security forces may have tipped off militants to the safe house location, he said.
Libya: 4 arrested over coordinated attack against U.S. - CBS News