Libyan protesters and security forces battled for control of Tripoli's downtown overnight, with snipers opening fire and supporters of longtime leader Muammar Gaddafi shooting from speeding vehicles, according to reports.
Meanwhile, Gaddafi's son, Seif al-Islam Gaddafi, warned that the country faced a bloody civil war if anti-government protesters refused to accept offers of reform.
Bursts of gunfire were heard overnight for the first time in the capital since violence broke out six days ago in Libya's second-largest city, Benghazi, where a hospital reported some 50 fatalities and 200 people injured on Sunday.
Eyewitnesses said anti-government protesters had poured into Tripoli's central Green Square where they were attacked by security and militia forces.
A central government building in the Libyan capital of Tripoli was set on fire Monday, according to Al-Arabiya TV. Protesters had also ransacked the headquarters of state television overnight and set ablaze the offices of the People's Committees which are the mainstay of the regime, said the report.
At least 233 people have been killed in Libya since protests broke out Feb. 15 against the autocratic Gaddafi's rule, according to U.S.-based group Human Rights Watch.
However, reports about the death toll vary, as Libyan authorities barred independent and foreign journalist from entering the country since the start of the unrest and media reports depend on phone conversations with witnesses — many of them doctors.
A statement issued by the State Department expressed grave concern that the number of deaths was unknown in the country because of a lack of access to news organizations and human rights groups.
The State Department spokesman, Philip Crowley, said that the U.S. had raised “strong objections about the use of lethal force” with several senior Libyan officials, including Musa Kusa, the foreign minister.
“Libyan officials have stated their commitment to protecting and safeguarding the right of peaceful protest. We call upon the Libyan government to uphold that commitment and hold accountable any security officer who does not act in accordance with that commitment,” he said.
The Libya protest followed similar uprisings in Tunisia and Egypt which have since mid-January ended the long rule of both countries' veteran leaders. Unrest has also hit Bahrain, Yemen, Algeria and Jordan.
Amid growing opposition to Gaddafi's rule, Seif al-Islam Gaddafi said in a televised speech that his father remained in charge with the army's backing and would fight "until the last man standing, even to the last woman standing."
His father still has control and is leading the fight, he said, but he added that some military equipment had been seized.
The younger Gaddafi accused exiles of fomenting violence and warned that the ongoing protests threaten to throw the north African country into a civil war. But he also acknowledged the regime made some "errors" in its handling of demonstrations, apologizing for the deaths of dozens of protesters at the hands of law enforcement officials. He pledged a new constitution and new liberal laws for Libya.
Gunfire could be heard ringing out as Gaddafi's lengthy speech was aired.
"He's threatening Libya and trying to play up on their fears. I don't think anyone in Libya who isn't close to the Gaddafi regime would buy anything he said," Najla Abdurahman, a Libyan dissident, told Al Jazeera after watching the address. "And even if there is any truth to what he said, I don't think it's any better than what the people of Libya have already been living with for the past 40 years. He promised that the country would spiral into civil war for the next 30 to 40 years, that the country's infrastructure would be ruined, hospitals and schools would no longer be functioning - but schools are already terrible, hospitals are already in bad condition."
In Libya's second biggest city, Benghazi, protesters were in control of the streets after days of bloody clashes and were swarming over the main security headquarters, looting weapons.
Libya has seen the bloodiest crackdown of any Arab country during the wave of protests sweeping the region.
Elsewhere in the Middle East:
A Yemeni teenager was killed and four people were wounded in a clash with soldiers in the southern port of Aden on Monday, witnesses said. They said soldiers opened fire at the youths who were throwing stones at their military patrol in the city's Khormaksar district. The death brings to 12 the number of people killed in unrest in Yemen since Thursday. Protesters are calling for the end of President Ali Abdullah Saleh's 32-year rule.
In Bahrain, predominantly Shia Muslim protesters continued to occupy the Pearl roundabout ahead of promised talks between opposition representatives and the Gulf nation's Sunni elite.
In Morocco, at least 2,000 people took to the streets of the capital Rabat on Sunday to demand a new constitution to ensure greater democratic freedom in the North African country.
In Iran, a huge deployment of police and pro-regime militiamen in capital Tehran prevented large-scale protests on Sunday, but Iranian opposition websites reported a number of clashes.
Algeria's Foreign Minister Mourad Medelci warned that anti-government protests that toppled rulers in Tunisia and Egypt will not spread to Algeria as part of a "domino effect" across the region. "The domino effect is an invention on the part of the media, including that of Algeria which is very free. I don't think it applies to Algeria. Algeria is not Egypt or Tunisia," he told Spanish daily newspaper El Pais.
And Tunisia is seeking the extradition of former President Zine al-Abedine Ben Ali from Saudi Arabia to face charges stemming from the violent crackdown on protesters last month, Tunisia's foreign ministry said on Sunday.