Three rockets, launched from across the border with Syria, hit the Bekaa valley of eastern Lebanon Saturday, causing no casualties, a security source told AFP.
"Three rockets launched from across the border with Syria hit an area that lies between the villages of Labweh and Jabbureh," the source said.
The rockets struck some 30 kilometres (20 miles) north of the city of Baalbek, a stronghold of the Lebanese Shiite movement Hezbollah.
"There were no casualties, but some trees in the area went up in flames," the source said.
Saturday's incident is the latest in a string of cross-border rocket attacks that have escalated as Hezbollah's involvement in Syria's brutal conflict has increased.
A close ally of the regime in Damascus, Hezbollah has sent elite fighters to assist the Syrian army in its bid to crush a rebellion aimed at bringing down President Bashar Al-Assad.
Syria's rebels see Hezbollah as much as an enemy as they do Assad's regime.
Now home to more than 700,000 Syrian refugees, fragile Lebanon has suffered a major spillover from the war.
Sectarian tensions pitting Sunnis against Shiites have escalated, and cross-border shellings, rocket attacks and shootings have hit several flashpoints in the border regions.
Last month, dozens died when massive car bombs, a week apart, hit Rweiss in Hezbollah's Beirut stronghold, and subsequently the majority Sunni city of Tripoli.