BEIRUT (AP) — Lebanese gangs backing the regime in Damascus smashed storefronts belonging to Syrian merchants on Wednesday and a powerful clan claimed it was holding more than 20 Syrians captives as the civil war across the border stirred tensions in this fragile Arab nation.

The flurry of violence came in response to Syrian rebels seizing a Lebanese man suspected of links to Shiite militant group Hezbollah, a strong supporter of Syrian President Bashar Assad’s regime along with Shiite power Iran.