( CNN ) -- A Sunni Islamist militant group claimed responsibility Saturday for a car bomb attack in Lebanon 's capital two days earlier which killed four people and injured dozens . The group , the Islamic State of Iraq and al-Sham , known as ISIS , said Thursday 's suicide blast in southern Beirut was the `` first small payment '' in a bigger push against the Lebanon-based Shiite militia Hezbollah . The al Qaeda-affiliated group has been pushing for a fundamentalist Islamic state carved out of northern Syria , while Hezbollah fighters have been supporting Syrian President Bashar al-Assad 's brutal push to crush a rebellion there . The ISIS statement said it targeted `` the Shiite Satan party '' -- meaning Hezbollah -- in order `` to crush its strongholds in the heart of its home in what is called the security zone in the southern suburbs of Beirut on Thursday in a first small payment from the heavy account that is awaiting those wicked criminals . '' The residential Harek Hreik district , where the car bomb exploded Thursday , is known as a Hezbollah stronghold . Car bombings in the same area of Beirut in July and August killed dozens and injured hundreds . And in November , a suicide bomb attack outside the Iranian Embassy , close to the neighborhood where Thursday 's attack occurred , killed two dozen people and injured about 150 . Long-standing tensions in Lebanon have been exacerbated by the civil war raging on its doorstep in Syria , where sectarian divisions reflect those in Lebanon . Regional turmoil . The Lebanese army said Saturday that the alleged chief of another Sunni jihadist group , the Abdullah Azzam Brigades , had died in custody after his health deteriorated . Majed Al-Majed , a Saudi national , was detained in the past few days by the Lebanese army . His group has claimed responsibility for bombings in Lebanon and elsewhere . Beirut-based Middle East analyst Rami Khouri told CNN that the recent surge in violence in Lebanon was part of larger , regional turmoil . `` We are seeing the greatest proxy war of modern times playing itself out in Lebanon and Syria and Iraq , that have now become really one battlefield in which two great ideological camps are fighting to the death like gladiators , '' he said . Political divisions and ideological tensions in Lebanon go back several decades , Khouri said , but they have been reinforced by the emergence of radical Islamist terrorist groups , linked to al Qaeda , following the U.S.-led invasion of Iraq . Hezbollah , which is backed by Iran , was designated as a terrorist group by the United States in 1995 . CNN 's Mohammed Jamjoom contributed to this report .
A Sunni Islamist group claimed responsibility for a suicide bombing in Beirut . The group , Thursday , claims it 's the ` ` first small payment '' in a bigger push against Hezbollah . Thursday 's car bomb detonated in a Beirut suburb known as a Shia stronghold . Lebanon has seen a surge in violence as tensions are exacerbated by Lebanon 's civil war .