BEIRUT — Lebanon moved to address the widespread possession and use of weapons in the country Wednesday after Shiite and Sunni groups used machine guns and rocket-propelled grenades in a deadly, hours-long street battle that was the worst clash in Beirut since 2008.The Information Ministry announced the formation of a committee headed by Prime Minister Saad Hariri to come up with proposals for confronting the problem, a day after the fighting in a residential neighborhood of Beirut killed three members of the Shiite Hizbullah group and a follower of the conservative Sunni al-Ahbash group.The announcement touches on one of Lebanon's most enduring problems: private, well-armed militias that operate outside the control of the central government.Hizbullah, the country's most powerful military force, maintains its own massive arsenal even though the group is now part of the government. At the end of Lebanon's 1975-1990 civil war, Hizbullah was the only group allowed to retain its weapons as protection against Israel.Nevertheless, many other groups held onto their weapons too and in recent years have been amassing more arms."Lebanon has always been a very volatile society," said Rami Khouri, director of the Issam Fares Institute of Public Policy and International Affairs at the American University of Beirut. "There are a lot of arms around. The central government never really had a monopoly on arms."Khouri said it is too early to gauge the significance of the new committee.The government has announced such plans before, to little effect.Witnesses told The Associated Press that Tuesday's fighting was touched off by a traffic dispute outside a mosque that escalated dramatically when local gunmen gathered reinforcements.Tensions between the Shiite and Sunni communities have been running high recently amid reports that Hizbullah members will be indicted in the 2005 assassination of former Prime Minister Rafik Hariri, once the country's top Sunni politician and father of the current prime minister.Abdul Qadir al-Fakhani, a spokesman for al-Ahbash, said his group was meeting with Hizbullah and the Lebanese army on Wednesday to ensure the situation does not flare up again.The two groups issued a joint statement late Tuesday saying the incident resulted from a "personal dispute and has no political or sectarian background."Nadim Houry, the Beirut director at Human Rights Watch, said Lebanon is caught in a "cycle of impunity" in such a heavily armed society."None of the gunmen is ever brought to justice. ... That is the real tragedy here," he said. "Gunmen are still above the law — and the civil war ended 20 years ago."On Wednesday morning, cleaning crews were sweeping the chunks of concrete that had been blown off the mosque by bullets and grenades. At least one gunman holding an AK-47 assault rifle had taken up position in a building across from the mosque.The fighting was the worst clash in Beirut since May 2008, when Hizbullah gunmen swept through Sunni neighborhoods after the pro-Western government tried to dismantle the group's telecommunications network.More than 80 people were killed in the 2008 violence, pushing the country to the brink of civil war.