Two Lebanese soldiers were killed on Friday in a clash between gunmen and the army in a village on the border with Syria, the military said.
"An army patrol was ambushed in the village of Arsal as it hunted a man wanted for several terrorist acts," the army said in a statement.
It said an army captain and soldier were killed while several others were wounded in the clash with an unspecified number of gunmen, who also sustained casualties.
"A number of military vehicles were badly damaged," the army said, adding that reinforcements were sent to seal off the area and hunt down the suspects.
A security source earlier gave a death toll of five soldiers and a gunman for the clash in the Sunni village. Islamists were involved in the attack, he told AFP on condition of anonymity.
An AFP correspondent saw ambulances leave Arsal and head for Baalbek, the main town in eastern Lebanon.
Lebanon's northern and eastern frontiers have seen spates of violence since the March 2011 outbreak of an uprising in Syria against President Bashar al-Assad, including cross-border shelling and gunfights.