Gunmen ambushed Lebanese troops in the east of the country on Monday, spraying their military vehicle with gunfire and rocket-propelled grenades, a senior military official said. Four soldiers were killed and an officer was wounded in the attack. The ambush on a major road near the town of Rayak comes after a recent push by Lebanese troops to crack down on the drug trade in the Bekaa Valley and carried the hallmarks of a revenge attack by clansmen. The official said the gunmen, traveling in three four-wheel drive vehicles, sped away after the attack. "The army is chasing the gunmen and calls on citizens not to shelter them," the official told The Associated Press, speaking on condition of anonymity in line with government regulations. The northern part of the Bekaa has Hizbullah strongholds but it is also a notoriously lawless region where Shi'ite clans involved in the drug trade have long held sway. Authorities occasionally crack down on drug dealers in the Bekaa, including a recently launched military campaign targeting members of one particularly powerful clan. An AP reporter and other witnesses in the eastern city of Baalbek said gunmen, believed to be members of the Jaafar clan, unleashed volleys of celebratory gunfire shortly after news of the military casualties were reported. Two members of the clan had been killed last month by the army. President Michel Suleiman, a former army commander, urged the military "not to be lenient with the attacking criminals in order to defend the dignity of the army and the country and protect national peace," according to a statement issued by the president's office. Interior Minister Ziad Baroud said the attack on troops is linked to the army crackdown on outlaws. "We will be working on practical steps as soon possible," he told Associated Press Television News. Baroud later said that Monday's attack would not deter the army from pursuing its campaign against criminals. The violence comes as Lebanon gears up for June parliamentary elections pitting the Iranian-backed Hizbullah and its allies against the pro-Western factions that currently hold a slim majority of the parliament seats.