"The events of last year, losing four brave Americans - Chris Stevens, Sean Smith, Glen Doherty and Tyrone Woods - brought home the reality of the challenges we face in the world," press secretary Jay Carney said in a statement marking the first anniversary of the Benghazi attack and the 12th anniversary of the terrorist attacks in New York, Washington and Pennsylvania
"As we near this day of remembrance, we continue to mourn the death of our cherished colleagues and honor their dedication to public service," Carney said. "We remain committed to bringing the perpetrators of the Benghazi attacks to justice and to ensuring the safety of our brave personnel serving overseas."
A powerful blast on the main street of Benghazi on the anniversary of the attack on the U.S. consulate there damaged a Foreign Ministry building and a branch of the Central Bank of Libya, witnesses said.
No deaths were reported in the explosion, CNN reported.
Bank branch manager Abdel Qader Mohammed said the explosion caused "material damage" to the financial institution, but did not affect its computer systems.
Two security guards stationed outside the bank sustained minor injuries in the blast, the Libya Herald reported.
"It was a massive explosion which caused a lot of damage to the two buildings," Abdullah Zaidi, a spokesman for Benghazi's joint security team, told the Libyan newspaper.
Benghazi resident Sami Berriwen told CNN if the blast had occurred about an hour later than it did, the street would have been full of people walking to school or work.
Scores of U.S. Marines were moved closer to Libya before the 12th anniversary of the Sept. 11, 2011, terrorist attacks on the United States and the first anniversary of the attack on the Benghazi consulate, CNN said.
U.S. officials told CNN that 250 combat-ready Marines were moved from their base in Moron, Spain, to the U.S. naval installation at Sigonella, Italy, enabling them to reach Tripoli in three to four hours if needed.