BEIRUT, Lebanon — At least three Lebanese Army soldiers were killed Friday in a shootout as they tried to arrest a resident of a village that has become a hub of refugees and where Syrian rebels often cross the border. Their target was also fatally shot.

There were conflicting reports about the nature of the clash, in which security forces were ambushed as they pursued a wanted man, but the episode played into fears that the accelerating influx of Syrians could spread the conflict into Lebanon.

The village, Aarsel, lies in the eastern Bekaa Valley, a mountainous region bordering Syria, and is a stronghold of support for the rebellion against the Syrian president, Bashar al-Assad. Syrian refugees who prefer to avoid areas of the Bekaa that are closely controlled by Hezbollah, an ally of Mr. Assad, have also crammed into the town.