By Stephen Kalin
BEIRUT (Reuters) - The death toll from a car bomb which ripped through the southern Beirut stronghold of Lebanon's militant group Hezbollah rose to 24 on Friday, and the government said the explosion may have been a suicide attack.
Thursday's blast, a month after a car bomb wounded more than 50 people in the same district of the Lebanese capital, came amid sectarian tensions over the intervention of Shi'ite Muslim Hezbollah against Sunni rebels in Syria's civil war.
Defense Minister Fayez Ghosn said a Syrian man had been arrested for suspected involvement in the July bomb attack, underlining the extent to which Lebanon has become embroiled in its neighbor's conflict.
The explosion on Thursday was the deadliest attack in the capital for years, engulfing a busy south Beirut street in flames and recalling scenes from its 1975-1990 civil war.
Interior Minister Marwan Charbel said investigators were checking CCTV footage taken in the moments before the explosion to see whether the van believed to have carried the bomb had been driven by a suicide bomber or detonated remotely.
"The first hypothesis is that the driver blew himself up, while the second hypothesis says that the car may have been blown up from a distance," Lebanon's National News Agency quoted Charbel as saying.
Reporters who arrived at the scene minutes after the explosion saw a burnt-out car near the center of the road, suggesting it was being driven when it blew up.
Hezbollah parliamentarian Ali Ammar told reporters in south Beirut on Friday the death toll had reached 24, while Health Minister Ali Hassan Khalil said 21 bodies were taken to hospitals and another 335 wounded people had been treated.
The discrepancy in death tolls may be the result of some bodies being too badly mutilated in the explosion to be collected or identified.
Among the dead were a family of five - a father, mother and their three daughters - who were killed in their car by the blast, which destroyed several vehicles and set fire to the lower floors of adjacent buildings, trapping residents.
Forensic investigators, emergency workers and security forces were still working at the site on Friday morning, amid burnt-out cars and charred facades of residential buildings.
Nearby, masked men fired in the air as the first funeral processions of victims of Thursday's explosion drove slowly through the subdued streets of densely-populated south Beirut.
As the country marked a day of official mourning, social media was flooded with pictures of the victims, and requests for information about people still missing.
Politicians from across Lebanon's diverse communities, including Sunni Muslims, Christians and Druzes, united to condemn the bloodshed in the Shi'ite neighborhood, some visiting the area to offer condolences.
But in a sign of how the Syrian crisis has polarized Lebanon, there was celebratory gunfire in the mainly Sunni city of Tripoli on Thursday night and reports of people distributing sweets.
The blast, a month after another car bomb wounded more than 50 people in the same district of the Lebanese capital, came amid sectarian tensions over the intervention of Shi'ite Muslim Hezbollah against Sunni rebels in Syria's civil war.
A Sunni Islamist group calling itself the Brigades of Aisha claimed responsibility for Thursday's attack and promised more operations against Hezbollah.
Residents of southern Beirut said Hezbollah, backed by Iran and Syria, had been on high alert and stepped up security in the area after warnings from Syrian rebels of possible retaliation for the group's support for President Bashar al-Assad.
Hezbollah leader Sayyed Hassan Nasrallah is expected to give his response later on Friday in an address marking the seventh anniversary of the end of Hezbollah's 2006 war with Israel.
Many Lebanese politicians pointed the blame at Israel in the immediate aftermath of the explosion, but Israeli President Shimon Peres said Lebanon should look elsewhere for the culprit.
"I was surprised," he told a joint news conference with United Nations Secretary-General Ban Ki-moon.
"Why should (they) look to Israel? (They have) a Hezbollah that collects bombs, that goes and kills people in Syria without the permission of the Lebanese government."
(Reporting by Dominic Evans, Laila Bassam and Mariam Karouny in Beirut and Allyn Fisher-Ilan; Editing by Andrew Roche)