New York-based Human Rights Watch said Libyan internal security forces also have arrested at least 14 people.

Hundreds of pro-government demonstrators also rallied in the capital, Tripoli, blocking traffic in some areas, witnesses said.

An opposition website and an anti-Qaddafi activist said unrest broke out during marches in four Libyan cities Thursday. Organizers were using social networking sites like Facebook and Twitter to call for nationwide demonstrations.

"Today the Libyans broke the barrier or fear, it is a new dawn," said Faiz Jibril, an opposition leader in exile.

Opposition website Libya Al-Youm said four protesters were slain by snipers from the Internal Security Forces in the eastern city of Al-Baida, which saw protests Wednesday and Thursday.

The website also said there was a demonstration Thursday in Benghazi, Libya's second-Largest city, and that security forces had shot and killed six people with live ammunition.

Switzerland-based Libyan activist Fathi Al-Warfali said 11 protesters were killed in Al-Baida on Wednesday night, and scores were wounded. He said the government dispatched army commandos to quell the uprising.

Libya Al-Youm said that protesters set out Thursday after the funeral for those killed a day earlier toward the State Security building, chanting "Free Libya, Qaddafi get out!"

Mohammed Ali Abdallah, deputy leader of the exiled National Front for the Salvation of Libya, said that hospitals in Al-Baida were complaining of a shortage in medical supplies, and that the government has refused to provide them to treat an increasing number of protesters.

Abdallah quoted hospital officials in the town as saying that about 70 people have been admitted since Wednesday night, about half of them critically injured by gunshot wounds.

Al-Warfali, head of the Libyan Committee for Truth and Justice, said two more people were killed in another city, Zentan, on Thursday while one protester was killed in Rijban, a town about 120 km southwest of Tripoli, where power was shut down Wednesday night and remained off Thursday.

Qaddafi's government has moved quickly to try to stop Libyans from joining the wave of uprisings in the Middle East that have ousted the leaders of Egypt and Tunisia. It has proposed the doubling of government employees' salaries and released 110 suspected militants who oppose him — tactics similar to those adopted by other Arab governments facing recent mass protests.

Qaddafi also has been meeting with tribal leaders to solicit their support. State television reported Tuesday that Qaddafi spoke with representatives of Ben Ali tribe, one of Libya's biggest clans and one that has branches in neighboring Egypt.

The official news agency JANA said Thursday's pro-government rallies were intended to express "eternal unity with the brother leader of the revolution," as Qaddafi is known.