A car bomb ripped through a Shiite neighborhood in south Beirut on Tuesday, killing four people and sending plumes of smoke over the area in the latest attack to target supporters of Lebanon's militant Hezbollah group.

It was the second bombing in the neighborhood of Haret Hreik this month amid a series of attacks that have shaken Lebanon in a spillover of Syria's civil war into its smaller neighbor. The violence has targeted both Sunnis and Shiites, and further stoked sectarian tensions that are already running high as each Lebanese community lines up with its brethren on opposing sides of the Syrian conflict.

Tuesday's explosion shattered shop windows and set cars ablaze on a crowded commercial street. Footage broadcast by the Hezbollah-owned al-Manar television station showed medics hauling a man on a stretcher out of the area as flames engulfed a building. Debris littered the pavement.

The Lebanese Red Cross, in a statement to the state-run National News Agency, said that along with the four killed, 35 people were wounded in the explosion.

A group known as the Nusra Front in Lebanon claimed responsibility for the attack, saying it was in retaliation for Hezbollah's military support of President Bashar Assad's forces in Syria. The claim, which could not be independently verified, was posted on the group's Twitter account. Its name suggested ties to the al-Qaida-linked Nusra Front in Syria, one of the most powerful rebel factions.

Lebanon's state media said a suicide car bomber was behind the attack. A security official, speaking on condition of anonymity because he was not authorized to talk to the media, said the vehicle was stolen and packed with 20 kilograms (44 pounds) of explosives.

"There was a car beeping, and then it exploded," an unnamed eyewitness told the Voice of Lebanon radio station. "Then we saw people on the ground — like every time."

Similar attacks have targeted Shiite areas in Lebanon in recent months, apparently the work of Syria-based Sunni rebels or militant Islamist groups fighting to topple Assad who have threatened to target Hezbollah strongholds in Lebanon in retaliation for intervening on behalf of his government in the conflict.

On Thursday, a car bomb struck the northeastern Shiite town of Hermel close to the Syrian border during rush hour, killing at least three people and wounding more than 20. And on Jan. 2, a bombing in Haret Hreik just meters (yards) from where Tuesday's attack occurred killed five people.

Another attack in November targeted the Iranian Embassy and killed at least 23 people. Iran is the chief patron of Hezbollah and an ally of Syria.

Lebanon's Sunni community has also been hit, most notably by a deadly double car bombing outside Sunni mosques in the northern Lebanese city of Tripoli in August. A December car bombing in Beirut killed prominent Sunni politician Mohammed Chatah.

The attacks raise the specter of a sharply divided Lebanon being dragged further into the Syrian conflict.

Shortly after Tuesday's bombing, clashes broke out in the northern Lebanese city of Tripoli, killing at least one person, said the security official. The city, with impoverished rival Sunni and Shiite areas, has seen frequent sectarian clashes linked to the war Syria that have killed dozens.

The latest fighting unraveled a tenuous truce in effect earlier in the morning, following clashes that broke out between the rival neighborhoods on Saturday.

Open gallery view Firefighters tackle the blaze caused by a car bomb in the Haret Hreik area of Beirut, January 21, 2014. Credit: AFP

Open gallery view People gather at the site of a bomb blast in the Haret Hreik area, in the southern suburbs of the Lebanese capital Beirut January 21, 2014. Credit: Reuters