The patrol begins at dusk every night, as the thuds from nearby artillery echo over the distant hills in southern Lebanon. Some scouts settle into hidden perches on the outskirts of town, keeping close watch on the roads leading into it. Others hop on their motorcycles and roam the streets, alerting the police to any suspicious cars or strangers.

The volunteer force describes itself as the first line of defense in Hasbayya, a mostly Druse and Christian town near the Lebanese-Israeli border. But the volunteers are not scanning for only the Israeli troops who invaded southern Lebanon last month as the conflict between Hezbollah and Israel escalated. They are also trying to prevent Hezbollah fighters from entering the town — and dragging it into the wider war.

The Israel-Hezbollah conflict was once contained to the border region, but has since enveloped swaths of southern and eastern Lebanon, a small Mediterranean country half the size of Vermont. Israeli airstrikes have rained down across the region, leveling beige stone homes and pulverizing villages into rubble. Hezbollah fighters have volleyed rockets back toward Israel and clashed with invading Israeli troops.

Israel’s military campaign has left few communities in the south untouched. Villages in the south where there is deep support for Hezbollah, an Iran-backed Shiite Muslim movement, have been flattened. Other mostly Christian, Sunni and Druse Lebanese towns that do not support Hezbollah have also been hit.

Lebanon has long been deeply divided along sectarian lines, mainly among its three dominant groups — Shiite and Sunni Muslims and Christians. Hezbollah is the most powerful political and military group in the country, representing many Shiites.

While Lebanese people are largely united against Israel’s onslaught, some in southern towns where Hezbollah does not hold sway say they feel trapped in the crossfire between Israel’s firepower and Hezbollah’s fighters. Desperate to shield their communities, some are cobbling together informal defenses of their own.

In Hasbayya, residents have established a neighborhood watch group. Some local leaders have negotiated with Hezbollah to keep its fighters from launching rockets from the town.

Officials within Hasbayya have also turned away Shiite Muslim families displaced from nearby villages where Hezbollah is dominant — a move that risks inflaming sectarian tensions that are always simmering. Local officials said they feared that Hezbollah fighters might be among the families, which could make them — and by extension the town — a target of Israeli strikes.

Locals know that Hezbollah, with its overwhelming military might, could go back on their pledge to steer clear of Hasbayya at any time and the town would be largely powerless to stop them. But for now, Hezbollah is treading lightly to maintain some good will with other sects and religious communities — and Hasbayya residents are doing what they can to deter the group.

“We don’t want any strangers or anyone related to Hezbollah here,” said Ghassan Halabi, the deputy mayor of Hasbayya, told visiting New York Times journalists last month. “It took us years to build this town and it could all be destroyed within minutes. We can’t allow that to happen.”

Sprawled across the foothills of Mount Hermon, Hasbayya is only six miles from the Israeli border. Winding roads connect clusters of houses and thickets of olive and pine trees, as well as ancient ruins dating back to the Crusader period. The town is home to about 30,000 people, mostly Druse Lebanese — adherents to a 1,000-year-old religion — as well as Christians and some Sunni Muslims.

These days, Hasbayya is cloaked in the din of war raging around it: The booms of artillery shells, the buzz of drones and the screech of Israeli jets overhead. When airstrikes hit in the distance, plumes of smoke curl into the air along the green slopes of mountains.

When Hezbollah began launching rockets into Israel last year in support of Hamas, prompting months of tit-for-tat strikes, local leaders in Hasbayya and other nearby Christian and Sunni villages approached Hezbollah officials in the area with a request.

We asked them “not to launch rockets from inside the town,” said Wissam Sliqqa, a Druse sheikh and local leader in Hasbayya. “We wanted to preserve the safety of our residents and ensure they could remain in their homes” and not be forced to flee north, he explained.

Hezbollah leaders agreed. But when the war intensified and Israeli airstrikes began pummeling villages on the edge of Hasbayya, panic took hold.

Worried that Hezbollah fighters might fall back to Hasbayya, dozens of residents volunteered with the municipality police to work shifts on a new neighborhood watch. They created a WhatsApp group for people in nearby villages to flag anything suspicious. The mayor, Abu Nassar, imposed an 8 p.m. curfew, after which all residents must remain inside their homes. After midnight, no cars are allowed to enter or drive through Hasbayya.

Those efforts are trying to fill the void left by the Lebanese National Army, which has never been strong enough to defend the country against invaders. Local officials know that their ragtag efforts can do little to protect Hasbayya against Israeli ground troops or airstrikes. But they hope the scouts can prevent Hezbollah fighters from setting up positions within the town. They can also alert residents in time to flee if Israeli troops do move forward.

“We’re worried,” said Kanj Nawfal, a municipal police officer who oversees the volunteer guards. “We are trying to be careful but if something happens,” he added, his voice trailing off. He wrung his hands, searching for the right words.

“This war is bigger than us,” Mr. Nawfal explained.

The town’s fears are rooted in the wreckage of nearby villages, damaged as the wake of destruction in Israel’s fight against Hezbollah has widened. In recent weeks, hundreds of people fleeing nearby villages flooded into Hasbayya looking for refuge.

Mohammad Fares, 34, arrived in late September from Chebaa, a mostly Sunni town wedged between Hasbayya and the Israeli border. The town had mostly been insulated from the strikes until late September when, around 2:30 one morning, an Israeli airstrike crashed into his neighborhood and killed a family of nine, according to residents.

Hours later, another airstrike landed in the town. Mr. Fares and his neighbors clambered into cars — some carrying more than a dozen people — and sped toward Hasbayya.

“It was like nowhere is safe anymore,” Mr. Fares said.

Mr. Fares, who is Sunni, found refuge in Kfeir, a village in greater Hasbayya, in a high school that was hastily converted into a shelter. In the days that followed, other families fleeing Marjayoun, a Christian city to the east, flocked to the school too. But local officials closed the doors when Shiite Muslim families leaving villages that are known to have deep-seated support for Hezbollah arrived.

“Families came and we told them, respectfully, there is no more space in our shelters,” said Mr. Halabi, the deputy mayor.

Mr. Halabi’s misgivings reflect the evolving pattern of Israeli airstrikes that have moved from solely Shiite pockets of Lebanon to also include areas home to mostly Christian, Sunni Muslim and Druse Lebanese, which were once considered safe. While many shelters in other towns have offered refuge to people of all religious backgrounds, strikes on houses and apartments hosting displaced families have stirred fears in Hasbayya that Hezbollah fighters are blending in with refugees, prompting Israel to strike them.

The limits of efforts to keep the town safe were made real last month: An Israeli airstrike leveled a guesthouse in the town, killing three journalists from Lebanese news outlets either owned by or seen as sympathetic to Hezbollah. It was the first strike within the town limits since the war escalated — and stoked fears that it was no longer off-limits.

“We don’t have problems with anyone, we don’t have outgoing rockets, we just want stability,” said Nayef el Hassaniyeh, 59, as he stood on his rooftop on the southern edge of the town one recent afternoon.

From his perch overlooking the mountains, Mr. Hassaniyeh patiently scanned the escarpments across from him. Almost every night since the conflict escalated, the spine of the mountains in the distance light up with the flash of airstrikes — a real-time map of the war’s path.

Mr. Hassaniyeh and some of his neighbors fear the strikes in the Sunni and Christian towns in the distance foreshadow Hasbayya’s fate if the war drags on. If cities where Hezbollah does not have support could be hit, they wonder, what is to stop Israeli airstrikes from raining down on theirs as well?

“This war has been imposed on us. Did we choose it as Lebanese? No. They imposed it on us,” Mr. Hassaniyeh said, referring to Hezbollah. “We just want to protect ourselves. We just want peace.”