The Lebanese army has deployed troops to create a buffer between two rival villages in the Bekaa Valley, as residents buried four Shia Muslim men who were killed in an attack on Sunday.

The men were smuggling fuel through the Qaa area when they were shot dead in the latest sectarian attack close to the border with war-wracked Syria.

When news broke of the killings, armed gunmen took to the streets of neighbouring towns, including Labweh, one of the first towns outside Arsal in northern Bekaa.

The situation remained tense into Sunday evening, with Hezbollah, the Lebanese Shia movement, and the army urging restraint from residents in the area.

On Monday, family members of the victims were holding funerals in Labweh and vowed retaliation for the ambush they believed was organised by residents from nearby Arsal and from across Syria.

Roadblocks

An elite unit of the Lebanese army set up roadblocks on the road between Labweh and mainly Sunni Arsal.

The civil war just a few kilometres across the border in Syria has inflamed tensions in the Bekaa Valley, where Sunni Muslims who support the uprising against Bashar al-Assad live close to Shia who back the Syrian president.

Al Jazeera's Nour Samaha, reporting from Labweh, said the clans in the village released a statement with their response to the attack on Monday evening.

"Residents told me the clans will give the culprits five to six days to turn themselves in, otherwise the situation will escalate," Samaha said.

"[Clan members] want to avenge the blood that has been spilled on Sunday. According to the residents of Labweh, there were two well-known residents of Arsal among the gunmen. They believe the others involved to be Syrians," she said.

"Some have said the ambush was in retaliation to the killing of an Arsal resident last week."

A military source said residents of Arsal denied any involvement in Sunday’s attack.

The recapture of the Syrian border town of Qusayr by Assad's forces, spearheaded by Hezbollah fighters, led to an influx of Syrian rebel fighters and civilians into Lebanon and more violence spilling over into the Bekaa region.

Rockets fired from areas controlled by Syrian rebels have targeted the Shia town of Hermel, while a Syrian helicopter crossed into Lebanon last week and fired at buildings in the town of Arsal, wounding several people.