at one blast

adverb2

1. •
   With one firing of a cannon or firearm; especially one whose ammunition is shotgun shot or grape shot, such that the multiple pieces of shot from one firing hit multiple birds or multiple soldiers.

   • Cannon, charged with grape, laid the men as flat as a pavement, exactly as a mighty wind levels standing grain at one blast. — 1898
2. •
   (figurative) At once, at the same moment in time.