Which of the following should you do first upon arriving at an accident scene?

Upon arriving at an accident scene, the first priority should be to ensure the safety of everyone involved and those in surrounding traffic. This means warning other road users about the accident to prevent further collisions and ensure that the scene is as safe as possible. Effective warning can be achieved by using hazard lights, setting up warning triangles if safe to do so, or guiding other vehicles to proceed with caution.

While switching off the vehicle engine, checking for casualties, and taking notes for insurance are all important actions to take, they come secondary to securing safety at the scene. Warning oncoming traffic minimizes the risk of additional accidents and allows emergency responders to work more effectively once they arrive.