The White House is yet to confirm the developments being reported from Libya.
"We're going to wait until we have full confirmation of what has happened... I'll make a statement when we do," US President Barack Obama told pool reporters travelling with him on his vacation.
"The end of the Gaddafi regime in Libya is a victory for the Libyan people and for the broader cause of freedom in the Middle East and throughout the world. This achievement was made possible first and foremost by the struggle and sacrifice of countless Libyans, whose courage and perseverance we applaud," said Senators John McCain and Lindsey Graham in a statement.
The two Senators said the uprising in Libya was inspired by the peaceful protest movements that succeeded in toppling long-ruling autocratic regimes in Tunisia and Egypt earlier this year.
"The liberation of Tripoli that is at last happening now marks a historic turning point in the Arab Spring and a victory for the advance of freedom globally," said Senator Joseph Lieberman.
"For the first time, a Middle Eastern dictator who tried to hang onto power by unleashing the most brutal possible violence is being deposed by his own people. The collapse of the Qaddafi regime thus sends a clear message to other autocratic regimes throughout the region -- from Damascus to Teheran -- that their day of reckoning too shall come," he said.
"The liberation of Libya is an achievement that belongs first and foremost to the Libyan people, whose bravery and determination has forever changed the course of their history, and ours. This is also a victory for the United States and our NATO allies, whose use of military force stopped Qaddafi when he was on the brink of slaughtering his own people and empowered them to secure their destiny for themselves. America should be proud of the role we have played," he said.
Lieberman said Gaddafi and his remaining loyalists have a choice now. "Rather than inflicting further pointless bloodshed and suffering, it is time for them to accept the will of the Libyan people and give up peacefully, before it is too late. There should be no doubt, anyone who persists in pursuing violence will be defeated," he said.
"The liberation of Tripoli is a great step forward on the long and difficult path of the Libyan people to freedom. We recognize that journey is still far from complete, and that there are still many perils and pitfalls ahead. But as long as the Libyan people continue on this path, they should know that America will stay by their side as a friend and ally."
