LABWEH, Lebanon (AP) -- The Lebanese army sent commandos to the tense border with Syria on Monday, as fears rose that the ongoing flight of rebels from one of their fallen strongholds into a flashpoint region of Lebanon would trigger the latest spillover of the Syrian civil war into its neighbor.
Lebanon has been on edge since the central Syrian town of Yabroud was taken by President Bashar Assad's troops on Sunday. Its rebel defenders started pouring into the Lebanese Sunni-dominated town of Arsal, which is surrounded by Shiite villages guarded by pro-Assad Hezbollah militants.
Sectarian violence between Lebanon's Sunnis and Shiites linked to Syria's civil war has left scores of people dead in recent months. The presence in the same area of Lebanon of Hezbollah and Sunni rebels -- who have just fought each other in Syria -- risks a polarizing new flare-up.
Many Lebanese Shiites back Assad's government, dominated by members of his minority Alawite sect, an offshoot of Shiite Islam. Hezbollah has fought alongside Assad's troops. On the other side, many Lebanese Sunnis back Sunni-dominated rebels.
On Monday, three rockets struck the predominantly Shiite towns of Labweh and Nabi Othman near Arsal, wounding at least one person and causing some damage, the army said. The army said the rockets were fired from inside Syria.
The barrage nonetheless appears to have sparked sectarian tensions in the area. Some angry Labweh residents claimed the rockets were fired from Arsal and closed off the main road between the two towns with sand barriers, guarded by dozens of Hezbollah fighters. They later closed other, smaller roads leading to Arsal, isolating the town from the rest of Lebanon.
Hezbollah fighters kept a close eye on Arsal from a distance and prevented journalists from going inside. Only Lebanese troops were able to drive on the road.
Syrian rebels and their sympathizers are believed to have considerable power in Arsal. Ramez Amhaz, the mayor of Labweh, called on the residents of Arsal to let Lebanese security forces take charge of the town "because now you cannot control the Syrians in Arsal."
"The people here will not be shelled and be subjected to rockets, then say that (Arsal residents) are our brothers," Amhaz told Lebanon's Al-Jadeed TV.
Earlier in the day, Lebanese troops and commandos in desert camouflage patrolled the rugged border area on foot. On one patrol, near the northeastern village of Fakiha, they came across an abandoned SUV and fired a rocket-propelled grenade at it, turning the vehicle into a fireball and leaving a four-meter-wide (yard-wide) crater on the ground. They could not take the chance of it being a car bomb.
"We took the decision to blow it up immediately, without searching it," an officer told The Associated Press at the scene, speaking on condition of anonymity in line with military regulations.
In footage broadcast live on state television in Damascus, Syrian army officers raised the national flag in Yabroud's main square and covered a rebel flag with banners praising Assad's troops.
The fall of Yabroud, a smuggling hub for the rebels trying to overthrow Assad, was a major gain for Syrian government troops. It was also the Syrian opposition's last stronghold in the vital border area. The campaign consolidated the government's hold on the capital Damascus and the central Syrian city of Homs.
Yabroud's fall came after months of fighting in the mountainous Qalamoun region between Assad's forces and Hezbollah fighters on one side and the rebels, mostly Islamist militant groups, on the other.
The Hezbollah fighters have been instrumental to Assad's success on the battlefield, and support from the Iranian-backed group appears to have tipped the balance into the government's favor in Yabroud.
In Lebanon, Sunni militants have in the past weeks carried out several suicide bombings and car bomb attacks in Shiite-dominated towns and suburbs of Beirut that are Hezbollah strongholds.
A Lebanese militant Sunni group claimed responsibility Monday for a car bombing the previous night in Nabi Othman, a predominantly Shiite town in Lebanon's Bekaa Valley that also has a significant Christian community.
The Nusra Front in Lebanon said in a statement posted on its Twitter account that the attack, in which two people were killed and 14 were wounded, was in revenge for Hezbollah's support for Assad and "a quick response" for the fall of Yabroud into Syrian government hands.
Syria's 3-year-old conflict has devastated the country, killing more than 140,000 people and forcing millions from their homes.
The crisis started as largely peaceful protests against Assad's rule in March 2011. It turned into a civil war after opposition supporters took up arms to fight a brutal government crackdown on dissent.