Lebanese soldiers stand guard at the site of a car bomb attack that hit a Hezbollah convoy travelling towards the Lebanese border crossing with Syria, on the Majdal Anjar-Masnaa road on July 16, 2013. (STR/AFP/GETTY IMAGES)

An explosion struck a convoy of cars in Lebanon’s Bekaa Valley on Tuesday, in what appeared to be the latest in a string of reprisal attacks against the Lebanese Shiite group Hezbollah for its role in the Syrian civil war.

The blast, which occurred near the Masnaa border crossing between Lebanon and Syria, targeted two vehicles carrying Hezbollah officials traveling toward Syria, a security official told Reuters news service. In recent weeks, Hezbollah has sent its fighters to support Syrian government forces against rebels seeking to oust President Bashar al-Assad.

It was not clear who was responsible, but Syrian rebels have threatened to strike Hezbollah in the past. Roadside bombs have targeted Hezbollah convoys on several occasions in the past month, while a car bomb rocked the group’s stronghold in southern Beirut last week.

Two people were injured in the explosion, according to Lebanon’s National News Agency.