BEIRUT (Reuters) – Four suicide bombers killed at least five people and wounded 19 more in a series of attacks in a Lebanese Christian village at the border with Syria on Monday, the latest violent spillover of the five-year-old Syrian war into Lebanon.

There was no immediate claim of responsibility for the attacks after 4 a.m. (2100 EDT) in the village of Qaa. Security sources said they believed Islamic State was responsible.

Lebanon has been repeatedly jolted by militant attacks linked to the war in neighboring Syria, where the powerful Lebanese Shi’ite group Hezbollah is fighting in support of President Bashar al-Assad.

Witnesses said the first bomber blew himself up after being confronted by a resident, Lebanese media reported. The others blew themselves up one after the other as people arrived at the scene.

The fourth bomber detonated himself as the head of the town council opened fire on him. “We saw there was a fourth suicide bomber walking… the head of the municipality shot at him, I did too, and this is when he blew himself up,” Dany Awad, the deputy municipality head, told Reuters.

The Lebanese army said four soldiers were among the wounded. They were part of a patrol that headed to the location of the first blast. The first of the bombers had blown himself up outside a house, followed by the others in an adjoining street.

The army imposed a security cordon in the area and was searching the village and nearby areas for suspects.

Lebanese security services have been on heightened alert for militant attacks in recent weeks. Islamic State had urged its followers to launch attacks on “non-believers” during the Islamic holy month of Ramadan, which began in early June.

Hezbollah leader Sayyed Hassan Nasrallah on Friday warned of a threat posed by militants based in the border area between Syria and Lebanon, saying they were still preparing car bombs in the area.

(Additional reporting by Reuters TV; Writing by Tom Perry/Laila Bassam; Editing by Dominic Evans)