Which action must not be taken at an accident scene until investigation is completed?

Disturbing the scene of an accident is crucial to avoid, as it can compromise the integrity of evidence essential for a thorough investigation. Maintaining the original conditions allows investigators to accurately reconstruct events leading up to the accident. This includes analyzing physical evidence, understanding the layout of the scene, and evaluating any contributing factors. By not disturbing the scene, it ensures that all necessary data can be gathered without alteration, which is vital for determining responsibility, preventing future incidents, and possibly addressing legal implications.

The other actions, such as taking photographs or collecting witness statements, are generally permitted and even encouraged as part of proper documentation and investigation procedures. Moving equipment might be appropriate in some situations to clear the area for safety reasons, provided that it does not disrupt evidence crucial to understanding the accident.