Cross-border clashes broke out late Wednesday on the restive Lebanese-Syrian frontier, a Lebanese security official told AFP, adding that there were no casualties.
"The Syrian army fired shells into Lebanon after unidentified armed men opened fire across the border near the village of Aboudiyeh" in northern Lebanon, the official said.
"One of the shells landed in the Nahr Kbir area," the official said on condition of anonymity. "Residents of the outskirts of Aboudiyeh fled their homes for the relative safety of the village centre."
Armed men in Lebanon used machinegun fire to shoot into Syrian territory, while the Syrian army responded with rounds fired from tanks and machineguns, the security official said.
"The Lebanese army has intensified its patrols, and though the firing has stopped, the situation remains tense," the official added.
Ever since the outbreak of the anti-regime revolt in Syria 19 months ago, multiple exchanges of fire have taken place across the border.
The Syrian army has also frequently fired shells across the border into Lebanon, officials have said.
Lebanon has made two official complaints against the Syrian authorities over territorial violations, while the regime of President Bashar al-Assad accuses Lebanon of allowing arms and fighters to enter into Syria illegally.
The international community and analysts have expressed fears that the conflict in Syria may spill over into the neighbouring small Mediterranean country.