BEIRUT, Lebanon — At least 16 insurgents from the Nusra Front, Al Qaeda’s wing in Syria, were killed in clashes with the Shiite group Hezbollah in eastern Lebanon on Sunday as the Nusra Front launched a major offensive, a person close to Hezbollah said.

Hundreds of Sunni Muslim insurgents from the Nusra Front attacked at least 10 Hezbollah bases along a mountain range close to the Syrian border, and killed two Hezbollah fighters, in the latest spillover of violence from the civil war next door in Syria.

“There are at least 16 dead from Nusra Front,” the person said. “Fighters from Hezbollah in the Bekaa region are joining the areas where the clashes are,” he added, referring to the region stretching across eastern Lebanon.

Hezbollah called on its fighters to defend the area, the person close to Hezbollah and other security officials said.