'Loud explosion' strikes Hezbollah stronghold in Beirut

A loud explosion struck a neighborhood in south Beirut this morning, Lebanese security officials said.

The nature of the explosion in the suburb of Bir el Abed, a stronghold of the Shi'ite group Hezbollah, was not immediately clear, the unnamed officials told the Associated Press.

Some Syrian rebel groups have threatened to strike in Lebanon after Hezbollah joined Syrian President Bashar al Assad's troops in their battle against opposition fighters.