Guards at a Palestinian guerrilla camp shot two Lebanese municipal policemen Monday near the coastal town of Naameh, 20 kilometers (12 miles) south of Beirut, witnesses and security officials said. One policeman was seriously wounded, security officials said, while the official National News Agency said police were investigating what sparked the shooting. The two policemen were on their way to collect tax arrears from factories in a nearby neighborhood when they came under fire from guards on the outskirts of the camp, security officials said. The officials declined to give their names because they were not authorized to talk to the media. The officials said the Palestinian guards who shot the policemen belonged to the Popular Front for the Liberation of Palestine-General Command, which is a small, Syrian-backed group that has been fighting Israel for decades. The Lebanese army sent troops to Naameh Monday as townspeople took to the streets and burned car tires to protest the shootings. The demonstration cut traffic connecting capital Beirut with southern Lebanon, the witnesses said. Protesters poured truckfulls of sands on the highway when the army intervened to reopen the road, leading to clashes in which at least two civilians were slightly injured, witnesses said.