Dozens were killed Wednesday when Syrian rebels set off a powerful tunnel explosion targeting an intelligence headquarters in Aleppo and clashed with regime forces, a monitor said. The Syrian Observatory for Human Rights said the blast hit a building housing the air force intelligence offices in the west of Syria's second city and was followed by heavy clashes. "The explosion and the fighting caused dozens of deaths on both sides," the Britain-based group said, adding that part of the building had collapsed.
The clashes pitted rebels from several factions against government troops supported by fighters from Lebanese Shiite militant group Hezbollah, a key backer of Syrian President Bashar al-Assad, it said. An AFP journalist in eastern Aleppo said the blast was loud enough to be heard across the city and some residents said it had felt like an earthquake.