Libyan security officials say unidentified gunmen have killed a military officer in a drive-by shooting in the eastern city of Benghazi.

Officials said Lieutenant Col. Ahmed Sweiry was instantly killed Thursday when unidentified assailants opened fire on him in al-Birkah district in Benghazi. Sweiry was working in the military's data department.

A health official said another soldier, a member of the commandos, was shot by unidentified assailants Wednesday also in Benghazi.

Officials spoke on condition of anonymity because they were not authorized to brief the media.

Much of Libya is experiencing a security vacuum but attacks against the military and security forces are particularly common in Benghazi, a stronghold of militias with roots in anti-Gadhafi rebel brigades. Some of the groups are Islamic hard-liners.