DAMASCUS, Syria— Rebels sent a wave of rockets slamming into regime strongholds in the central city of Homs on Thursday, triggering a succession of massive explosions in a weapons depot that killed at least 40 people and wounded dozens, an opposition group and residents said.
The attack — one of the most potent against progovernment districts in the area — overshadowed a rare trip by President Bashar Assad to a former opposition bastion outside the capital, Damascus, during which he defiantly vowed in front of troops to defeat the rebels fighting to topple him.
The huge explosion in the Homs district of Wadi Dahab delivered a jolt to Assad's regime, which for weeks has been boasting of achievements against the rebels in the strategic Homs region and the suburbs of Damascus.
''The achievements on the ground speak for themselves,'' Assad told soldiers in Daraya, a few miles south of the capital. ''Without you we would all be slaves to the countries that want to subjugate us. But the Syrian people will never be slaves. Not in the past, present, or future."
The attack in Homs targeted the neighborhoods of Zahra, Akrama, and Wadi Dahab — all populated mostly by Alawites, the same sect as Assad.
It showed that rebels fighting to oust Assad are still able to strike back despite significant advances by the military that have bolstered the confidence of the regime.
The blasts sent a massive ball of fire and a black mushroom cloud into the sky and caused widespread damage and panic among residents, many of whom are supporters of Assad. Firefighters struggled for two hours to put out the flames.
''The first explosion knocked people off their feet,'' said one Homs resident, adding that successive smaller explosions lasted for more than an hour. He declined to be named, fearing retaliation.
He said the blasts were so strong they cracked the walls of buildings and blew doors and window frames off their hinges. The slum of Wadi Dahab has one- or two-story buildings.
The Britain-based Syrian Observatory for Human Rights, which monitors the fighting via a network of activists on the ground, said at least 40 people were killed and 120 were wounded — some critically — when rockets struck the arms depot in the southern Wadi Dahab and ignited the fire.