CAIRO — Protesters clashed Friday with security forces in the Libyan capital of Tripoli and fought for control of key eastern cities in the most serious challenge to dictator Moammar Gadhafi's 42 years in power.
The Libyan bloodshed appeared to be the worst in the Middle East on a day that also saw troops fire on pro-democracy protesters in the Persian Gulf sheikdom of Bahrain and intense confrontations pitting protesters against security forces and government loyalists in Yemen.
Across the Gulf of Aden from Yemen, riot police used tear gas and batons to break up a protest by several thousand antigovernment demonstrators in Djibouti, a city-state of 750,000 people in the Horn of Africa that hosts the only U.S. military base in Africa.
"The Arab world is experiencing a domino effect," said Ghada el Sherif, 40, a demonstrator in Cairo.
Human rights group said 24 people had been killed across Libya, though activists say the count may be far higher.
Libya demonstrates both the power and the limits of the Arab uprisings. The country, though the most isolated in the region, is not disconnected enough to black out the news of autocrats' falling in Egypt and Tunisia. But information about what is happening inside Libya — and the ability of protesters to mobilize world opinion on their behalf — is far more limited.
"The international community is watching," said Issa Abdel Majeed Mansour, an opposition figure based in Oslo, Norway. "Why isn't anyone helping us?"
In Libya, residents reached by telephone said the most intense unrest was in the eastern city of Benghazi. As many as 15,000 people gathered in front of the courthouse in the city on Friday, and security forces withdrew from at least part of the city by the afternoon, residents said.
Amnesty International, citing sources at Benghazi's main hospital, put the casualty toll since Wednesday at 46 dead and more than 100 injured, and accused Gadhafi's security forces of "recklessly shooting at antigovernment protesters."
In Bahrain, at least 66 people were injured by live ammunition and tear gas inhalation.
Government forces opened fire on hundreds of mourners marching toward Pearl Square in the capital of Manama on Friday, sending people running away in panic amid the boom of concussion grenades. But even as the people fled, at least one helicopter sprayed fire on them and a witness reported seeing mourners crumpling to the ground.
Even as ambulances rushed to rescue people, forces fired on medics loading the wounded into their vehicles. That only added to the chaos, with people pitching in to evacuate the wounded by car and doctors at a nearby hospital saying the delays in casualties reaching them made it impossible to get a reasonable count of the dead and wounded.
The crown prince, Sheik Salman bin Hamad Al Khalifa, went on Bahrain TV to call for calm, saying, "Today is the time to sit down and hold a dialogue, not to fight."
The violence came a day after both President Barack Obama and Secretary of State Hillary Rodham Clinton urged the leaders of the country, a longtime ally, to show restraint. Obama reiterated that message on Friday and condemned the violence in Bahrain, Libya and Yemen.
"I am deeply concerned by reports of violence in Bahrain, Libya and Yemen. The United States condemns the use of violence by governments against peaceful protesters in those countries and wherever else it may occur," Obama said. "We express our condolences to the family and friends of those who have been killed during the demonstrations."
With the petroleum-fueled U.S. economy dependent on Middle East oil and Washington closely allied with Israel, the United States for decades backed many of the region's despotic rulers and monarchs, choosing the iron-fisted stability they provided over the frustrations of populations denied political and human rights.
But as Egypt's 18-day uprising gathered pace before ousting President Hosni Mubarak, Obama swung U.S. sympathy toward the largely young pro-reform protesters.
In Libya, the violence represented the biggest crisis for Gadhafi since he seized power in a bloodless 1969 coup and imposed one of the region's most ruthless authoritarian systems on his oil-rich country of 6.4 million people. Establishing independent political parties or trade unions there is a crime punishable by death.
The worst violence occurred in Benghazi, Beyida, Darnah and other towns along the eastern coast of the Gulf of Sidra, close to the Egyptian border.
A group calling itself the Libya Youth Movement began unprecedented anti-Gadhafi broadcasts over an Internet radio station, while recordings of ordinary Libyans describing the turmoil were posted on another website, feb17voices.
Mohammad Eljahmi, a Libyan expatriate living in the Boston area who was in touch with acquaintances in Libya, said anxiety had replaced his "initial exhilaration" over the anti-Gadhafi protests.
"This man has been in power 43 years," he said. "He can make this ugly."
The violence in the Bahraini capital, Manama, erupted after the funerals of four protesters, who'd been killed a day earlier when security forces charged sleeping anti-government protesters who were occupying central Pearl Square.
Information from McClatchy Newspapers and the New York Times was used in this report.