BEIRUT — A powerful car bomb tore through a bustling south Beirut neighborhood that is a stronghold of Hezbollah on Thursday, killing at least 18 and trapping dozens of others in an inferno of burning cars and buildings. At least 280 people were wounded. It was the bloodiest attack yet linked to Syria’s civil war.
The blast is the second in just over a month to hit one of the Shi’ite militant group’s bastions of support, and the deadliest in decades. It raises the specter of a sharply divided Lebanon being pulled further into the conflict next door, which is being fought on increasingly sectarian lines pitting Sunnis against Shi’ites.
Syria-based Sunni rebels and militant Islamist groups fighting to topple Syria’s President Bashar Assad have threatened to target Hezbollah strongholds in Lebanon in retaliation for intervening on behalf of his regime in the conflict.
Thursday’s explosion ripped through a crowded, overwhelmingly Shi’ite area tightly controlled by Hezbollah, turning streets lined with vegetable markets, bakeries, and shops into scenes of destruction.
Dozens of ambulances rushed to the site and firefighters used cranes and ladders to try to evacuate terrified residents from burning buildings. Some fled to the rooftops of buildings and civil defense workers were still struggling to bring them down to safety several hours after the explosion.
The blast appeared to be an attempt to sow fear among the group’s civilian supporters and did not target any known Hezbollah facility or figure.
Hezbollah’s Al Manar TV and Red Cross official George Kattaneh said the death toll was at least 18.
The army, in a statement, said the explosion was caused by a car bomb. It called on residents to cooperate with security forces trying to evacuate people trapped in their homes.
Syria’s conflict has spilled across the border into its neighbor on multiple occasions in the past two years.
Fire from Syria has hit border villages, while clashes between Lebanese factions backing different sides have left scores dead.
But direct attacks against civilian targets were rare until Hezbollah stepped up its role in Syria. Since then, its support bases in southern Beirut have been targeted.
Rockets have been fired at suburbs controlled by the group on two occasions, wounding four people. On July 9, a car bomb exploded in the nearby Beir al-Abed district, wounding more than 50 people.
Thursday’s explosion, however, was the bloodiest single attack in south Beirut since a 1985 truck bomb assassination attempt targeting top Shi’ite cleric Mohammed Hussein Fadlallah in Beir al-Abed left 80 people dead.
It came despite rigorous security measures taken in the past few weeks by Hezbollah around its strongholds, setting up checkpoints, searching cars, and sometimes using dogs to search for bombs.
It also came a day before Hezbollah’s leader was scheduled to give a major speech marking the end of the month-long 2006 war with Israel.
The explosion occurred on a commercial and residential main street in the Rweiss district, about 100 yards away from the Sayyed al-Shuhada complex where Hezbollah usually holds rallies.
Hezbollah leader Sheikh Hassan Nasrallah, who has lived in hiding since his group’s 2006 month-long war with Israel, made a rare public appearance at the complex on Aug. 2, where he addressed hundreds of supporters.
He was to speak again on Friday from a location in southern Lebanon, but his speeches by satellite are often transmitted to followers at the complex.
Panicked Hezbollah fighters fired in the air to clear the area and roughed up photographers, smashing and confiscating some of their cameras following the explosion.
Hezbollah lawmaker Ali Ammar called the blast a ‘‘terrorist’’ attack and called for restraint among the group’s supporters.
He suggested the group’s political rivals in Lebanon were responsible for creating an atmosphere that encourages such attacks.