BEIRUT (AP) -- Lebanese forensic experts collected evidence Friday at the scene of a massive explosion in a southern suburb of Beirut that killed 22 people and wounded more than 300, the deadliest blast in the area in nearly three decades.
Security officials said they were investigating the possibility that Thursday's blast in Hezbollah's bastion of support was carried out by a suicide bomber.
Lebanese troops cordoned the area of the explosion where more than a dozen charred cars were scattered on the street amid heavily damaged buildings, preventing residents and shop owners from entering.
Some residents vowed that such attacks will only strengthen their support of the militant Hezbollah group and its leader.
Thursday's car bomb struck a crowded street in the Rweiss district in Beirut's southern suburbs, an overwhelmingly Shiite area and stronghold of Hezbollah. The explosion sent a massive plume of black smoke billowing into the sky, set several cars and buildings ablaze and trapped dozens of residents in their homes for hours.
The explosion occurred about 100 meters (yards) away from the Sayyed al-Shuhada complex where Hezbollah usually holds rallies.
Thursday's blast came a day before Hezbollah's leader Sheik Hassan Nasrallah was scheduled to give a speech marking the end of the monthlong 2006 war with Israel. Nasrallah was expected to address the explosion in the speech later Friday.
The bombing was the second in just more than a month to hit one of the Shiite group's bastions of support, and the deadliest since 1985 when a blast in the area killed 80 people. Many people in Lebanon see the attacks as retaliation for Hezbollah's armed support for President Bashar Assad in neighboring Syria's civil war.
The group's fighters played a key role in a recent regime victory in the town of Qusair near the Lebanese border, and Syrian activists say Hezbollah guerrillas are now aiding a regime offensive in the besieged city of Homs.
Syrian rebels have threatened to retaliate against Hezbollah for intervening on behalf of the Assad regime. Thursday's car bombing raises the worrying specter of Lebanon being pulled further into the Syrian civil war, which is being fought on increasingly sectarian lines pitting Sunnis against Shiites.
"We will always support Sheik Hassan," said Hassane Qassem, a 56-year-old retired soldier whose house was damaged by the blast. Neither he nor his wife were hurt, but he said their domestic help from Bangladesh suffered minor head injuries and was rushed to a nearby hospital.
"I entered the bathroom and the whole building shook," said the man standing about 50 meters (yards) from his home. He said he helped rush wounded people to ambulances before he entered the barber shop of his friend in the building.
"I found my neighbor and friend Hussein under a wall inside his shop. I closed his eyes and recited prayers for him then left," Qassem said.
On July 9, a car bomb exploded in the nearby Beir al-Abed district, wounding more than 50 people. Since then, security measures by Hezbollah have become tighter with group members setting up checkpoints searching cars and preventing strangers from parking cars in crowded areas.
Lebanese security officials said they are investigating whether the blast was carried out by a suicide attacker. They said the attacker may have tried to park the car in front of a building but was prevented by residents. He moved few meters up then the vehicle blew up, the officials said on condition of anonymity in line with regulations.
Interior Minister Marwan Charbel said that security officials were conducting DNA tests on body parts discovered near the blast.
Charbel said the death toll rose Friday to 22. Health Minister Ali Hassan Khalil said 336 were wounded by the blast.
The fate of some people is still missing is unknown, as some of the bodies have been totally charred. The Lebanese army urged people who have relatives missing to come forward and give DNA samples.
State-run National News Agency said that among those missing since were a father and his three children.
Tensions between Lebanon's own Sunni and Shiite communities have risen sharply, particularly since Hezbollah began fighting openly in Syria. Lebanese Sunnis support the rebels fighting to topple Assad, a member of a Shiite offshoot sect.
Lebanese President Michel Suleiman blamed Israel for the blast, while Israel's President Shimon Peres said Israel "has nothing to do" with it.
"I was surprised that the President of Lebanon said that Israel is again responsible; why should he look to Israel?" Peres asked. "He has Hezbollah collecting bombs and killing people in Syria without the approval of the Lebanese government."
Associated Press writer Ryan Lucas contributed to this report.