LONDON (CBS NEWS) - An explosion inside the Syrian national security headquarters in Damascus targeted ministers from President Bashar Assad's regime who were meeting with defense officials on Wednesday, killing two of the most senior members of Assad's inner circle, including his brother-in-law.
The Syrian Army said Defense Minister Gen. Dawoud Rajha and his deputy, Asef Shawkat, were both killed in the explosion. Shawkat, Assad's brother-in-law, also held the title of Deputy Chief of Staff.
Other ministers and military officials were seriously wounded in the explosion, according to the state-run TV channel.
The Syrian army confirmed the deaths, saying Rajha and Shawkat, seen at left, had been "martyred" in a "terror attack."
"The attack makes Syria, its armed forces, people and leadership, more determined to stand up to terror groups and amputate the arm of anybody who seeks undermine Syrian security," continued the army statement.
Syrian State TV denied another report that Interior Minister Mohammed al-Shaar was dead, saying he was hospitalized in stable condition.
CBS News correspondent Elizabeth Palmer reports that in spite of increasing attacks in recent weeks, Damascus had remained a bubble of relative normality in Syria. Wednesday's crippling blow, however, will almost certainly put an end to that image - even among those regime supporters who have tried to ignore the encroaching reality.
Fierce gun battles and other explosions were reported around the capital following the attack on the security headquarters, including at least four blasts reported near military installations in Damascus.
Opposition leader Kamal al-Labwani told al-Arabiya, a pan-Arab satellite channel, that a member of the rebel Free Syrian Army planted a TNT and C-4-based device inside the building ahead of the meeting, and then detonated the bomb remotely before fleeing to safety. There were conflicting claims, however, from other opposition figures, some of them claiming a suicide belt had been used in the attack.
Reporting from the scene of the explosion, CBS News' George Baghdadi said the blast did not appear to be very large. There have been previous bomb attacks inside Syria targeting regime officials, but they have been much larger explosions and targeting much lower-ranking members of the government and security forces.
The national security headquarters is among the most tightly secured buildings in Damascus. If rebel forces did in fact remotely detonate a bomb, the individual who planted the device likely was an insider. Officials told Al Jazeera that the person who planted the device was one of the cabinet member's personal bodyguards.
The armed uprising against Assad's regime has intensified rapidly in recent weeks, with mounting military and political defections eroding his family's long-time grip on power as rebel forces engage his troops more frequently in Damascus, the president's seat of power.
The Free Syrian Army announced in a statement on Monday the launch of an offensive dubbed "the Damascus volcano and earthquakes of Syria," reports CBS News' Khaled Wassef.
The statement said the FSA had begun carrying out attacks on all security stations and branches in Syrian cities and the countryside. It called for attacks on military forces and pro-regime militia checkpoints across the country, as well as cutting off all international highways.
The Muslim Brotherhood, a political party which has risen to new heights in nearby Egypt since the overthrow of President Hosni Mubarak, is the main faction in the biggest Syrian opposition group, the Syrian National Council. The Brotherhood issued a statement Tuesday urging the Syrian people to rise up and back the rebels locked in what the group called a "decisive battle" against Assad's troops in Damascus.
Elsewhere around the world, diplomatic wrangling over how to handle the Syrian crisis continued ahead of a scheduled vote Wednesday on a new United Nations Security Council resolution.
Russia, a longtime Syrian ally that has along with China twice vetoed previous U.N. action against the Assad regime, accused Western powers of fomenting conflict.
"Instead of calming the opposition down, some of our partners are inciting it to go on," Foreign Minister Sergey Lavrov said, according to RIA Novosti news agency Wednesday.
U.S. Defense Secretary said the situation in Syria is "rapidly spinning out of control" and "it is more essential than ever" for the international community to broker a peaceful transition of power.