On Capitol Hill on Thursday, members of Congress celebrated reports of the death of Libyan strongman Moammar Gaddafi.But some also warned that his absence has created a dangerous vacuum of leadership in Libya.

The country’s new prime minister, Mahmoud Jibril, announced Gaddafi’s death on Thursday morning. The former dictator was apparently killed in the final stages of the battle to control Sirte, Gaddafi’s home town and a final holdout against rebels in an eight-month war backed by NATO airstrikes. Sirte has fallen to the rebels.

“The death of Muammar Qaddafi marks an end to the first phase of the Libyan revolution,” Sen. John McCain (R-Ariz.), a strong supporter of the Libyan rebellion in Congress, said in a statement. “Now the Libyan people can focus all of their immense talents on strengthening their national unity, rebuilding their country and economy, proceeding with their democratic transition, and safeguarding the dignity and human rights of all Libyans.”

But Gaddafi’s death also creates a dangerous moment in Libya, said Rep. Tom Rooney (R-Fla.), who had been skeptical of American involvement in the NATO campaign against the leader. Rooney said that Libya’s loosely organized rebellion must somehow create a stable government--and ward off interference from terrorist groups or other countries hostile to democracy.

“What you’re going to see is bad actors come and try to seize control of the situation, and I’m hopeful that the so-called Libyan rebels...will be able to quell that,” Rooney said in a telephone interview. “I just don’t think that they will be. That’s when we’re going to have to make the decision” of whether to send U.S. or other Western troops into the country to try to protect the fledgling government.

If the United States does send troops in, Rooney said, “that’s going to be war number three.”

Rep. Ileana Ros-Lehtinen (R-Fla.), who chairs the House Foreign Affairs Committee, said in a statement that Gaddafi’s fall shows that “the will of free people cannot be suppressed forever.”

“Qaddafi’s fall gives hope to all those around the world who are oppressed by tyrants. These dictators brutalize their own people, endanger global security, and protect one another.,” Ros-Lehtinen said, mentioning Gaddafi’s admiration for Cuban leader Fidel Castro and Venezuelan leader Hugo Chavez.

Illinois Sen. Mark Kirk (R) praised the Obama administration’s handling of the Libyan crisis.

“Today marks the end of Qadhafi’s reign and a new opportunity for freedom, prosperity and a voice in the global community for Libyans,” Kirk said in a statement. The administration, especially Secretary of State Hillary Rodham Clinton, “deserve our congratulations.”

The lawmakers’ statements used alternate spellings of Gaddafi’s name.