DAMASCUS, Syria — Suicide bombers targeted security compounds in Damascus and a car bomb exploded in a pro-regime district there Sunday, killing at least eight people, the latest in a surge of civil war violence in the capital.

In northern Syria, a car bomb killed 12 soldiers in Aleppo, according to the Britain-based Syrian Observatory for Human Rights, which relies on a network of activists in Syria for information. It had no other details, and the government did not comment.

In neighboring Lebanon, meanwhile, fierce clashes erupted between the Lebanese military and supporters of a hard-line Sunni Muslim cleric, in the latest spillover from Syria. Six Lebanese soldiers were killed, according to the army, which vowed to hit back with an "iron hand."

Heavy fighting with machine guns and rocket-propelled grenades in Sidon caused panic in the southern coastal city, which until recently had been largely spared the violence hitting other areas. Many people who were spending the day on the beach hurried home, while others living on high floors came down or fled to safer areas. Gray smoke billowed over parts of the city and residents caught in the fire appealed for help.

The fighting broke out in the predominantly Sunni city after supporters of Sheikh Ahmad al-Assir, a virulent critic of the powerful Shiite militant Hezbollah group, opened fire on an army checkpoint.

The military issued a statement confirming that six soldiers died in the shooting, including three officers. It said the shooting was unprovoked.

Syria's state-run news agency SANA said three suicide bombers blew themselves up while trying to break into the Rukneddine police station in northern Damascus, killing five people and wounding several others. SANA said three would-be suicide bombers also tried to break into the Criminal Security Branch in the southern Bab Mousalla area but were caught by security forces before they could detonate their explosives.

Activists confirmed the death toll.

SANA said a car bomb exploded in Mazzeh 86 district in the capital, killing three people, including a 3-year-old boy. Residents of the district are mostly Alawites, an offshoot Shiite sect that President Bashar Assad's family belongs to. The opposition forces fighting against Assad's regime are mostly Sunni Muslims.

Nobody immediately claimed responsibility for the Damascus explosions, but they bore the hallmarks of al-Qaida-linked groups that have joined forces with rebels fighting to oust Assad.

The attacks in Syria's two largest cities came as government forces pressed an offensive on the outskirts of the capital.

SANA carried a statement by the Interior Ministry saying that the Damascus attacks were a "new escalation by terrorist groups," a term used by the government to refer to the rebels.

More than 93,000 people have been killed in Syrian conflict that started in March 2011 as peaceful protest against Assad's rule. In the past year, the war has taken on sectarian overtones.

The conflict has increasingly spilled across Syria's borders.

The clashes in Sidon centered on the Bilal bin Rabbah Mosque, where al-Assir preaches. The cleric is believed to have hundreds of armed supporters in Sidon who fought back Sunday. Dozens of al-Assir's gunmen also partially shut down the main highway linking south Lebanon with Beirut.

By Sunday evening, the army had besieged the mosque, sealing off access to it from all directions, and was going after al-Assir and his supporters, who have been agitating for months.

The NNA report said Assir was believed to be hiding inside the mosque with several of his followers.

The cleric and his followers support Sunni rebels in the Syria conflict, and he has threatened to clear apartments in Sidon where Hezbollah supporters live.

Sunday's clashes in Sidon deepened tensions in Lebanon. on edge since the Syrian conflict began more than two years ago.

Lebanese President Michel Suleiman called an emergency meeting of the security cabinet for Monday. NNA also reported sporadic shooting in the volatile city of Tripoli in the north, and the army announced additional force deployments in around Beirut.

The violence came a day after an 11-nation group that includes the U.S. met in the Qatari capital of Doha to coordinate military aid and other forms of assistance to the rebels.

Syria's al-Thawra newspaper, the mouthpiece of the government, assailed the Friends of Syria meeting.

"It's clear that the enemies of Syria are rushing to arm the terrorists to kill the chances for holding the Geneva conference," the newspaper said, referring to a U.S.-Russia initiative for bringing Assad's government and rebels together to negotiate an end to the crisis.

The Syrian paper pledged that the army would "continue the showdown to eliminate terrorism and restore security and stability."

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Surk reported from Beirut. Associated Press writer Jamal Halaby in Amman, Jordan contributed to this report.