Widespread violence erupted on the streets of Damascus on Wednesday as Syrian security forces and pro-government militias lashed out in revenge for a bombing that killed at least three of the most crucial figures in the nation’s military establishment, calling into question President Bashar al-Assad’s control even over his capital.

The blast targeted a meeting of the top security chiefs charged with overseeing a crackdown against the country’s 16-month-old revolt. The bombing suggested that the rebels have managed to penetrate the most loyal core of Assad’s inner circle of advisers.