BEIRUT (AP) -- A suicide bomber struck the National Security building in the Syrian capital Wednesday, killing the defense minister and President Bashar Assad's brother-in-law -- the harshest blow to the Syrian regime since the uprising began.
Syrian state-run TV said the blast came during a meeting of Cabinet ministers and senior security officials in Damascus, where four straight days of clashes pitting government troops against rebels have sent tensions soaring.
Defense Minister Dawoud Rajha, 65, a former army general, was the most senior government official to be killed in the Syrian civil war as rebels battle to oust Assad. Gen. Assef Shawkat, the deputy defense minister and one of the most feared figures in Assad's inner circle, also was killed. He was married to Assad's older sister, Bushra.
Interior Minister Mohammed Shaar was wounded and in stable condition, state TV said.
Republican Guard troops surrounded the nearby al-Shami Hospital, where some officials were taken for treatment, witnesses said.
The Assad family has ruled Syria for four decades, creating an ironclad and impenetrable regime. Wednesday's attack was a nearly unheard-of strike on the inner circle.
Although it was unclear who was behind the attack, the high-level assassinations could signal a turning point in the 16-month conflict as the violence becomes increasingly chaotic.
Besides a government crackdown, rebel fighters are launching increasingly deadly attacks on regime targets, and several massive suicide attacks this year suggest al-Qaida or other extremists are joining the fray.
Activists say more than 17,000 people have died since the uprising began in March 2011.
The Syrian army released a statement saying its forces will continue to fight.
"Whoever thinks that by targeting the country's leaders they will be able to twist Syria's arm is disillusioned because Syria's people, army and leadership are now more determined than ever to fight terrorism ... and cleanse the nation from the armed gangs."
Rajha was the most senior Christian government official in Syria. Assad appointed him to the post last year. His death will resonate with Syria's minority Christian population, who make up about 10 percent of Syria's population and have generally stood by the regime.
Christians say they are particularly vulnerable to the violence sweeping the country of 22 million people, and they are fearful that Syria will become another Iraq, with Christians caught in the crossfire between rival Muslim groups.
The blast came on the same day the U.N. Security Council was scheduled to vote on a new resolution aimed at pressuring the Syrian regime to comply with a peace plan.
But Russia remained at loggerheads with the U.S. and its European allies over any mention of sanctions and Chapter 7 of the U.N. charter, which could eventually allow the use of force to end the conflict in Syria.
The state-run news agency SANA reported that Wednesday's blast was aimed at the National Security building, a headquarters for one of Syria's intelligence branches and less than 500 meters (yards) from the U.S. Embassy.
Police had cordoned off the area, and journalists were banned from approaching the site.
Earlier Wednesday, SANA said soldiers were chasing rebels in the Midan neighborhood, causing "great losses among them." The Britain-based Syrian Observatory for Human Rights said army helicopters attacked the neighborhoods of Qaboun and Barzeh.
Diplomacy so far has failed to stop the bloodshed, and there appeared to be little hope that the U.N.'s most powerful body would unite behind a plan.
The key stumbling block is the Western demand for a resolution threatening non-military sanctions and tied to Chapter 7 of the United Nations Charter, which could eventually allow the use of force to end the conflict in Syria.
Russia is adamantly opposed to any mention of sanctions or Chapter 7. After Security Council consultations late Tuesday on a revised draft resolution pushed by Moscow, Russia's deputy U.N. ambassador Alexander Pankin said these remain "red lines."
Russia has said it will veto any Chapter 7 resolution, but council diplomats said there is still a possibility of last-minute negotiations.