Sydney: A hostage who died during a siege in a downtown Sydney cafe was killed when she was struck by fragments of a bullet fired from a police officer's gun as authorities stormed in to end the 16-hour standoff, a lawyer told an inquest today.

Katrina Dawson, a 38-year-old lawyer who was among 18 people taken hostage last month by a gunman, died after being hit by six fragments of a police bullet that had ricocheted off a hard surface, Jeremy Gormly, a lawyer assisting the coroner, told the Glebe Coroner's Court.