DAMASCUS, Syria (AP) -- 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 pro-government 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 kilometers (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," he said.
The attack in Homs targeted the neighborhoods of Zahra, Akrama and Wadi Dahab, which are 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 over an hour. He declined to be named, fearing retaliation.
He said the blasts were so strong they cracked the walls of some buildings and blew doors and window frames off their hinges. The slum area of Wadi Dahab houses mostly one- or two-story buildings.
The Britain-based Syrian Observatory for Human Rights, which closely 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 part of Wadi Dahab and ignited the fire.
Activists in the city corroborated that account, saying at least 40 were killed and many others wounded. They said the regime is known to keep arms depots in those areas.
An official at the governor's office in Homs said six people were killed and 145 wounded when about 10 rockets slammed into the neighborhood of Zahra and the nearby sports stadium. He said one rocket struck a civil defense center, referring to the Wadi Dahab area, although he did not directly address the weapons depot.
He spoke on condition of anonymity because he wasn't authorized to release the information.
Government officials often give conflicting figures than those provided by the opposition. There was no immediately explanation for the discrepancy, and state-run media did not report the incident.
The attack was claimed on Facebook by the al-Haq brigade, one of a myriad of groups fighting in Homs that are loosely affiliated with the main rebel umbrella group, the Free Syrian Army. Homs-based activist Abu Bilal also said al-Haq brigade targeted the weapons depot with Grad rockets.
Assad's visit to Daraya was his first known public trip outside the capital, his seat of power, in more than a year. On the previous trip he visited the battered Baba Amr district in Homs after troops seized it from rebels in March 2012.
On Thursday, Syrian TV showed him walking among soldiers in the battered suburb, chatting and shaking hands with soldiers atop tanks who pumped their fists in the air and flashed the victory sign.
"I deliver to you today a message of thanks from every Syrian," he told the troops.
The visit is the latest sign of confidence from Assad, whose troops have been on the offensive and scored significant gains in recent months.
More than 100,000 people have been killed since the uprising against the Assad family's four-decade rule began in March 2011. The revolt later escalated into a civil war, which has uprooted millions of people from their homes.
Daraya was held by rebels for months. It took the army weeks of heavy fighting to regain control of the area earlier this year.