Beirut • A powerful car bomb exploded in a Hezbollah stronghold in the southern suburbs of Beirut on Tuesday, wounding at least 53 people in the most troubling sign yet that Syria's civil war is beginning to consume its smaller neighbor.
The blast in the heart of the Shiite militant group's bastion of support raised the worrying specter of Lebanon being pulled into the violent Sunni-Shiite struggle in the region, with sectarian killings similar to those plaguing Syria and Iraq.
The Syrian conflict, now in its third year, is whipping up sectarian fervor. Sunni-Shiite tensions have risen sharply, particularly since Hezbollah raised its profile by openly fighting alongside President Bashar Assad's forces. Lebanese Sunnis support the rebels fighting to topple Assad.
While there was no immediate claim of responsibility, there have been growing fears in Lebanon that Hezbollah could face retaliation for its now overt role fighting alongside Assad's troops. The group's fighters played a key role in a recent regime victory to retake control of the strategic town of Qusair, near the Lebanese border, where rebels held sway for more than a year. Syrian activists say Hezbollah fighters are now aiding a regime offensive in the besieged city of Homs.
Syria-based rebels and militant Islamist groups have threatened to target Hezbollah strongholds in Lebanon in retaliation.
The car bomb struck a bustling commercial and residential neighborhood in Beir el-Abed, an area of particularly strong Hezbollah support, as many Lebanese Shiites began observing the holy month of Ramadan. The blast went off in a parking lot near the Islamic Coop, a supermarket usually packed with shoppers.
Beir el-Abed is only few hundred yards from what is known as Hezbollah's "security square," where many of the party's officials live and have offices.
Tuesday's attack inflamed long-simmering tensions in Lebanon, where deadly clashes between Shiites and Sunnis have grown increasingly common as the civil war in Syria has taken on ever darker sectarian overtones. Some Sunnis in Lebanon, many of whom support Syria's rebels, have expressed resentment over what they see as Hezbollah's unchecked power in the country.
The anger was clear among residents of Dahyeh, Hezbollah's stronghold in Beirut's southern suburbs. At the scene of the explosion, some cursed Sunni politicians and Syrian rebels, calling them Israeli agents.
Tuesday's explosion was one of the biggest in the capital's southern suburbs since the end of Lebanon's 15-year civil war in 1990, and a major breach of a tightly controlled, high security area.
"It is a large area, heavily populated. No force in the world can protect every area and every street," Hezbollah lawmaker Ali Moqdad said.
The breach raised questions about the group's ability to control the anger it helped unleash through its involvement in the Syrian civil war. At the same time, Lebanese Sunni groups have also joined the fight alongside Syria's rebels, offering logistic and other support.