Investigators in southern Beirut have been combing through the blast site of Thursday's attack that killed six people and injured dozens more.<br /><br />The pro-Hezbollah area has been targeted several times over recent months.<br /><br />Some believe the explosion was a retaliation against Hezbollah, fighting alongside forces of Syria's President Bashar al-Assad. But unlike previous bombings, there have been no immediate claims of responsibility.<br /><br />Al Jazeera's Zeina Khodr reports from southern Beirut.
