A security source revealed Tuesday that six Hezbollah fighters and around 30 jihadis were killed in clashes that erupted in the Qalamoun border region one day earlier. Monday's clashes ended with Hezbollah fighters seizing two new hilltops in Qalamoun, three weeks into an offensive to oust jihadis from the rugged border region, according to Hezbollah's Al-Manar TV. The Al-Manar report said Hezbollah fighters captured several highland areas northeast of the outskirts of Lebanon's Nahleh, without reporting casualties. Monday's deaths bring to at least 22 the number of Hezbollah fighters killed since the offensive got underway on May 4. The number of militant casualties since the start of the offensive is unclear, but is likely to be in the hundreds. Hezbollah and the Syrian army have destroyed dozens of jihadi bases and driven the Nusra-led militants north toward the outskirts of Lebanon's northeastern town of Arsal, where Nusra and ISIS have taken foothold. But tensions remain between the rival jihadis. A separate security source Tuesday said Syrian national Husam Mrad, who is reportedly a member of ISIS, was kidnapped late Monday from a Syrian refugee camp in Arsal and taken to the town's outskirts. Mrad was abducted hours after ISIS kidnapped Syrian national Ahmad Saifeddine, a Nusra militant. Tensions between the jihadi rivals have soared in recent weeks, with the Nusra-led Army of Conquest declaring earlier this month that it would "eradicate ISIS" from Qalamoun for harassing and attacking other Syrian rebel groups.