A security official said the midday attack in Haret Hreik targeted an area where the terrorist organization Hezbollah has broad backing, the (Beirut) Daily Star reported.
No one has claimed responsibility for the bombing, officials said.
Analysts said they believe a recent rash of bombings in predominantly Shiite neighborhoods are payback for the roles Lebanonese militias and Hezbollah have taken in the civil war in Syria, the New York Times said. Shiites support Hezbollah, which has sent fighters to augment Syrian President Bashar Assad's troops against opposition forces seeking to oust him. Lebanon's Sunnis identify with the mostly Sunni rebels.