"The people of Qaa sleep in fear now," said Mansur Saad, mayor of the village which straddles the border with Syria.
"They live with the constant worry that violence will erupt at any moment, especially if gunmen from across the border escape into Lebanon."
The sleepy village, located in a pastoral region where fruit and vegetable fields are dotted with Bedouin tents, on October 18 was the scene of a military incursion which left two local residents -- both Syrians -- dead and sparked panic.
A third Syrian was killed in a raid on Aarsal, a village 10 kilometres (six miles) south of Qaa.
Residents of Qaa, who for decades have maintained warm ties with their Syrian neighbours, say the once-friendly border soldiers who cross over daily for morning coffee are increasingly on edge as the seven-months revolt against Bashar al-Assad's regime continues.
The usually bustling official crossing of Joussiyeh, in Qaa, meanwhile has been shut down and an eerie silence has settled over the area where the Lebanese army or security forces are nowhere to be seen.
"We have asked the Lebanese army to strengthen its presence in the area and set up posts at the border in order to prevent infiltration and make sure such incidents do not re-occur," Saad told AFP.
But the Lebanese government, largely dominated by the powerful militant group Hezbollah, a strong ally of the Syrian regime, has for the most part stayed mum on the issue.
Washington and the United Nations, meanwhile, have condemned the incursions, seen as a bid by Damascus to clamp down on arms smuggling and prevent dissidents and army defectors from crossing over to Lebanon.
Adel's home in Qaa still bears the marks of Syrian gunfire on October 18 that prompted his family and neighbours to flee.
"They were scared to death," said the 35-year-old merchant.
"Many women and children in our village are still spending the night with relatives in other towns for fear of more raids."
Lebanon and Syria share a 330-kilometre border but have yet to agree on an official demarcation. Apart from the Joussiyeh crossing, the rest of the border area at Qaa is separated only by dirt mounds and a tiny creek allowing people to cross freely and smuggling activities to flourish.
The home of Ahmad Abu Jabal, killed in the October 18 raid on Qaa, symbolises the village's ties to Syria. The humble abode straddles both countries with the front door located in Lebanon and the back door in Syria.
The circumstances surrounding Abu Jabal's death remain unclear. While Syrian authorities claim he was an arms smuggler, his cousin told a different tale.
Speaking to AFP on condition of anonymity, he said Abu Jabal was gunned down as he tried to prevent Syrian troops from detaining his brother who was later also killed.
In the nearby village of Aarsal, where a third Syrian was killed earlier this month, residents say a long-running political feud with Damascus is now in the open.
"Our town has been in an open war with the Syrian regime since 2005," said Mohammed al-Hujairi, mayor of the majority Sunni town.
He was referring to the 2005 assassination of Sunni ex-premier Rafiq Hariri, widely blamed on Syria by the country's pro-Western camp.
"Foreign troops are entering our land and the Lebanese government has not lifted a finger," said Hujairi.
"If these violations continue, we will have no choice but to defend ourselves in any way we can, even if it is only with stones."