(CNN) -- Syria's defense minister, Dawood Rajiha, was killed Wednesday in a suicide bombing at a national security building in Damascus, state-run media reported.

The bombing took place during a meeting of ministers and security officials, state-run TV said.

The opposition Syrian Observatory for Human Rights said initial reports indicate a car bomb caused an "intense explosion" in Damascus.

The explosion marks a pivotal point in the 16-month Syrian crisis and comes days after heavy violence reached the seat of President Bashar al-Assad's regime. Rajiha is the highest-ranking known member of the Syrian regime to be killed.