Updated 8:14 a.m. ET
TRIPOLI, Libya A powerful car bomb exploded Wednesday near Libya's Foreign Ministry building in the heart of the eastern coastal city of Benghazi, security officials said, exactly one year after an attack there killed the U.S. ambassador and three other Americans.
The early morning blast targeted a building that once housed the U.S. Consulate under the rule of King Idris, who former Libyan dictator Muammar Qaddafi overthrew in a 1969 bloodless coup. The explosion caused no serious casualties, though several passers-by were slightly wounded, officials said.
The bomb blew out a side wall of the building, leaving desks, filing cabinets and computers strewn among the concrete rubble. It also damaged the Benghazi branch of the Libyan Central Bank along a major thoroughfare in the city.
No group immediately claimed responsibility for the attack, which also comes on the 12th anniversary of the Sept. 11, 2001, terror attacks in the U.S. The security officials spoke on condition of anonymity because they were not authorized to speak to journalists.
Qaddafi was killed after eight-month uprising that descended into a civil war in 2011. Since then, successive Libyan interim governments have failed to impose law and order. The country remains held hostage by unruly militia forces initially formed to fight Qaddafi. The militias, which have huge stockpiles of sophisticated weaponry, now threaten Libya's nascent democracy.
Car bombs and drive-by shootings since the end the civil war routinely kill security officials in Benghazi, the birthplace of the uprising.
Tawfiq Breik, a lawmaker with the liberal-leaning National Forces Alliance, said that the attacks will continue as long as Libya lacks a strong national army and police.
"Even with so many officials assassinated, no one held accountable," Breik said. "No one arrested. The state is disabled."
The car bombing comes exactly one year after al Qaeda-linked militants stormed the U.S. mission in Benghazi and a nearby U.S. building, killing U.S. Ambassador Chris Stevens and three other Americans.
The attack sparked a wave of criticism toward President Barack Obama and his administration for its handling of the attack and its aftermath. The administration closed 19 diplomatic posts across the Muslim world for almost a week last month out of caution over a possible al Qaeda strike likely in response to the Benghazi criticism.
On Aug. 9, Obama told reporters that the U.S. was still committed to capturing those who carried out the deadly consulate assault. Obama said his government has a sealed indictment naming some suspected of involvement. Officials said earlier that the Justice Department had filed under seal the first criminal charges as part of its investigation of the attack.
The Associated Press reported in May that American officials had identified five men who might be responsible for the attack. The suspects were not named publicly, but the FBI released photos of three of the five suspects, asking the public to provide more information about the men.
Some in the photographs are thought to be members of Ansar al-Shariah, the Libyan militia group whose fighters were seen near the consulate prior to the violence. Other witnesses reported seeing the leader of an Islamist militia group called Abu Obaida Bin Jarrah, whom U.S. officials told the AP is among the suspects in the sealed indictment. The leader has repeatedly denied being involved and says he abandoned the militia and now works in construction.