"I'm not in France or Venezuela … I'm still here" in Tripoli, Gadhafi said in the face of rumors he had fled the country, admonishing anyone who would listen not to believe those "dogs in the media," CNN reported.
Egyptians in Libya have returned home by the thousands, joining hundreds of Libyan refugees, and witnesses arriving in London from Tripoli told CNN the scene they fled was "horrific" with "lots of gunfire."
Protests against Gadhafi's government began Thursday and reached Tripoli Monday, as one protester in exile said helicopters fired on demonstrators.
The United States ordered non-essential diplomats to leave the nation while it said it was "gravely concerned with disturbing reports and images coming out of Libya," the State Department said in a statement.
"We are working to ascertain the facts, but we have received multiple credible reports that hundreds of people have been killed and injured in several days of unrest -- and the full extent of the death toll is unknown due to the lack of access of international media and human rights organizations," the statement said.
The statement said department officials raised "our strong objections to the use of lethal force against peaceful demonstrators" to a number of Libyan officials.
In Benghazi, Libya's second-largest city, anti-government demonstrators celebrated on the streets on news the city was now under their control, The Washington Post reported.
Faiz Jibril, an opposition leader living in exile, told the Post his contacts inside Libya told him the eastern portion of the country was liberated from pro-government forces. He also said helicopter gunships were targeting protesters in Tripoli and protesters walking to the capital from Misruata, another city the protesters took over, he said.
In Tripoli, pro-government forces met demonstrators with guns and fighting, and the protests were quelled, one resident speaking to the Post via Skype said. He said the uprisings seemed to be spontaneous and lacked leadership or organization.
"Everyone is out to topple the regime altogether," the man said. "It is a people's revolt. Everyone is acting instinctively."
Gadhafi's son and heir-apparent Monday warned in a televised speech the North African nation could descend into anarchy if his father were ousted and called anti-government elements inside the country "national traitors."
U.N. Secretary-General Ban Ki-moon conducted an "extensive conversation" with Gadhafi and stressed the violence "must stop immediately," the United Nations said in a statement.
Tribal leaders also criticized Gadhafi, and reports of soldiers defecting to the opposition spread through the country, the Post said. In addition, senior Libyan officials reportedly were resigning from their posts because of the killings.
Human Rights Watch said at least 233 people have died in the protests, citing information from health officials that could not be independently verified.
Suleiman Saghir, a Libyan who crossed into Egypt at Salloum, told al-Masry al-Youm conditions in Libya were "atrocious and unimaginable."
Ali al-Essawi, Libya's ambassador to India, resigned from his post Monday and called for Gadhafi to step down, the Post said.
In Stockholm, Libyan Embassy staff said members gave their notice to quit to protest Gadhafi, The Local reported.
"We, the undersigned staff of the Libyan Embassy in Stockholm, condemn the genocide that is taking place in Libya against civilians as a consequence of the legitimate demands for a life of dignity and without the despot Gadhafi's continued misrule and corruption," translator Sayed Jalabi, receptionist Hamid Kassem and secretary Abdelali Mahfouf wrote in a letter Monday. "We find the situation intolerable for us. We do not want to be passive when we see that people are rising against the tyrant despite the obvious risk that they may shed their own blood."
Amr Moussa, Arab League secretary-general, called for an end to the violence in Libya, al-Masry al-Youm said. Moussa said he is "gravely concerned" about the events in Libya, saying protesters' demands for reform, change and development are legitimate.
Saif al-Islam Gadhafi, one of Gadhafi's seven sons, proposed implementation of democratic reforms in the restrictive country while warning civil war, a return to colonialism and poverty would occur if opposition protests continue.
"We can speak rationally, we can spare the blood, we can stand all together for the sake of Libya," the son said on Libyan state television.
Conversely, if protests go on, "forget about democracy, forget about reform. ... It will be a fierce civil war," he said.
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