Upon confirmation of a release in accordance with §334.74 of this title (relating to Release Investigation and Confirmation Steps) or after a release from the aboveground storage tank (AST) or underground storage tank (UST) system is identified in any other manner, owners and operators must perform the following initial response actions within 24 hours of a release:(1) report the release to the agency (e.g., by completed telephone call, facsimile transmission, or electronic mail);(2) take immediate action to prevent any further release of the regulated substance into the environment, including shutting down the leaking AST or UST system as determined necessary; and(3) identify and mitigate fire, explosion, and vapor hazards.