Dawood Rajiha al-Assad's brother-in-law and Hasan Turkmani, al-Assad's security adviser and assistant vice president, were killed in an explosion

(CNN) -- A deadly attack on top Syrian officials Wednesday delivered the harshest blow yet to President Bashar al-Assad's regime, bringing the bloodshed into his inner circle, and even his family.

Defense Minister Dawood Rajiha, Deputy Defense Minister Assef Shawkat -- al-Assad's brother-in-law -- and Hasan Turkmani, al-Assad's security adviser and assistant vice president, were killed in an explosion at a national security building in Damascus, state TV reported. Others were injured, state TV said.

The attack, during a meeting of ministers and security officials, was coordinated by several rebel brigades in Damascus, said the deputy head of the opposition Free Syrian Army, Col. Malek al-Kurdi.

The government described it as a suicide bombing. But al-Kurdi said a remote control was used to detonate an explosive device planted inside the meeting room.

Video from a Damascus suburb showed Syrians rejoicing after news spread of the bombing.

Al-Assad quickly named Gen. Fahd Jassem al-Freij as defense minister, state-run news agency SANA said.