The Syrian army closed in on Syrian rebel factions Monday in central Zabadani as they advanced cautiously to take control of the last rebel-held town in the Qalamoun region near the Lebanese border. Syrian troops locked in on militants from all sides. "They are under fire," the source said. The source, who spoke on condition of anonymity, revealed that, raising the death toll to four. At least three Syrian army soldiers have also been killed in the battle, the source said. A separate security source said the Al-Jamaiyat neighborhood in western Zabadani witnessed heavy clashes overnight Monday as Syrian army hit rebel posts with four barrel bombs. The Syrian army's offensive in Zabadani is largely considered an attempt to bolster their control of land routes between Lebanon and Syria and cut rebel supply lines. Battles Sunday, which broke through four axes in Zabadani, inflicted heavy casualties on the militants. The decision to launch the offensive in Zabadani came after negotiations with rebels failed to secure the militants' withdrawal from the area, which is located 50 kilometers northwest of Damascus and 12 kilometers northeast of Lebanon's Masnaa border crossing.