"I take responsibility... I take this very personally," Hillary Clinton told the CNN in Lima, the capital of Peru, as the issue threatened to snowball into a major controversy in US presidential elections where latest opinion polls showed Republican challenger Mitt Romney forging ahead.
"I'm in charge of the State Department... The president and the vice president wouldn't be knowledgeable about specific decisions that are made by security professionals. They're the ones who weigh all of the threats and the risks and the needs and make a considered decision," she said as polls show that the handling of the Libyan crisis might hit President Barack Obama's re-election chances.
"I take this very personally," she said. "So we're going to get to the bottom of it, and then we're going to do everything we can to work to prevent it from happening again, and then we're going to work to bring whoever did this to us to justice."
She said an investigation now under way will ultimately determine what happened at the US Consulate in Benghazi, where Ambassador Chris Stevens and three other Americans were killed on Sept 11.
Her comments came just hours before the two presidential candidates - Obama and Romney - would be locked in the second of their three high-stake debates tomorrow.
The Libyan issue is coming to the forefront with media reports said that the White House has put special operations strike force on stand-by and moved drones into the skies above Africa ready to hit militant targets from Libya to Mali.
The Obama Administration initially attributed the attack on a mission to an anti-Islam video that resulted in an instant protest. Later, it dubbed the assault as a terrorist attack.
The top Republican Senators were quick to term Clinton's remark as "laudable", but said the White House is trying to avoid any responsibility whatsoever.