AL TAL, Syria -- A bomb targeting Syria’s military leadership killed the country’s defense minister Wednesday and at least two other high-ranking officials, sparking questions about how long the besieged government of President Bashar Assad can remain in power and highlighting the differences between the United States and Russia over what steps should be taken to curb the violence that’s sweeping Syria.

The deaths of Defense Minister Dawoud Rajha, his deputy, Assef Shawkat, who was Assad’s brother-in-law, and Hassan Turkmani, a former defense minister, marked the first time the rebels who are fighting to topple Assad have managed to kill members of his inner circle. According to Syrian state media, the blast also wounded Interior Minister Mohammed Shaar.

Rebels said the men were part of Assad’s “crisis management” team, which met daily at different locations throughout the capital. Rebels have been targeting the group for months. In May, the rebels claimed to have killed Shawkat by poisoning him.

U.N. Syria envoy Kofi Annan, who’s been struggling to impose a peace plan on Syria’s warring factions, condemned the bombing, as did Russian Foreign Minister Sergey Lavrov. The Obama administration declined to do so, instead repeating its call for Assad to step aside. “It is precisely because of the ongoing campaign by President Assad against his own people that we are seeing a situation that is getting worse and worse,” White House spokesman Jay Carney said.

In some of Damascus’ northern suburbs, fighters reacted to the news with unrestrained glee, breaking into spontaneous song and repeatedly shouting, “God is great.” But by nightfall there were reports in parts of the city that pro-government fighters were taking revenge against residents of neighborhoods that support the rebels.

Fighting raged in parts of Damascus throughout the day, though the threat to the government from that violence was unclear. For the first time since the uprising against Assad began 16 months ago, Syrian government forces began shelling rebels in the city proper over the weekend. But the areas where the fighting is taking place are largely the same ones that previously have been the scene of violence and where militancy has been heightened in recent months by an influx of refugees from Homs and other conflict areas who openly support the rebellion.

“The consequences of what happened today are not clear,” said Radwan Ziadeh, an anti-government activist who’s focused on documenting civilian and rebel casualties during the conflict. “But I don’t think Bashar Assad can control Damascus anymore.”

Residents of the city reported attacks by the military after the blasts.

“They are shelling my street,” said a resident of Yarmouk, in southern Damascus, who spoke by telephone only on the condition that he not be identified, for fear of government retribution. “I asked my parents to leave three days ago, but I don’t know what has happened to my uncles.”

“There are many tanks coming into Yarmouk. Mosques are being turned into field hospitals. There are a lot of refugees coming from al Hajar, al Tadamon,” another Yarmouk resident, said, referring to adjacent neighborhoods where fighting was taking place.

“They are staying in the schools,” said the man, who also asked not to be named, referring to the refugees. “There is no place to go.”