Two people were killed Saturday when gunmen stormed a police post in eastern Lebanon after clashing with army troops following the arrest of an alleged Syrian jihadist, security sources said.
The two men were reportedly killed trying to prevent a group of gunmen from storming the police post inside the town of Arsal, which lies on the border with Syria, security sources said.
Lebanon's official National News Agency also reported the attack and deaths.
Local media reported that the gunmen were holding a number of policemen, but there was no immediate confirmation.
A security source said the gunmen had also briefly detained several soldiers, but they were subsequently released.
Security sources and residents said troops and unidentified gunmen exchanged fire after the detention of Imad Ahmed Jomaa, a suspected member of Al-Nusra Front, the Syrian affiliate of Al-Qaeda.
The clashes broke out near Arsal, where many residents support the uprising against Syria's President Bashar al-Assad.
Local media said the army had deployed in force in the area after gunmen surrounded several army checkpoints following the arrest, and that two military helicopters were headed to the region.
The army said in a statement it had arrested Jomaa at noon and that he had admitted to belonging to Al-Nusra Front.
Arsal is a predominantly Sunni town hosting tens of thousands of Syrian refugees and has supported the Sunni-led uprising against Assad.
The area has been the scene of frequent tensions with Lebanese security forces, as well as air raids and cross-border shelling by Syrian troops who say they are targeting rebels holed up in the mountainous region.
Al-Nusra Front has been fighting against Syrian government forces along with other rebel groups.
It has also fought against the Islamic State (IS), a radical jihadist group which has declared a "caliphate" in territory it has seized straddling Syria and Iraq.
Despite the conflict between the two jihadist groups, they have also fought alongside each other in some areas of Syria, including the Qalamun region which borders Lebanon.
A monitoring group said at least 50 members of Al-Nusra and the IS were killed in fighting in the area late Friday against regime troops and their allies from Lebanon's Shiite movement Hezbollah.
Violence from Syria's conflict has regularly spilled over into Lebanon, which is hosting more than one million Syrian refugees.
The border area has been particularly volatile, though bomb attacks claimed by groups fighting in Syria or linked to Syria-based factions have also targeted other regions, including Beirut.