If you discover a leak in a fuel line, what should you do first?

Shutting off the fuel at the tank is the most critical immediate action to take when a leak in a fuel line is discovered. This step directly addresses the source of the risk by stopping the flow of fuel, which can prevent a potential fire or explosion. Fuel is highly flammable, and any leak can create a hazardous condition, especially if it comes into contact with an ignition source.

By shutting off the fuel supply, you minimize the amount of fuel that can escape into the environment, thereby reducing the danger associated with the leak. After securing the fuel supply, it would then be appropriate to evaluate the situation further, including whether to evacuate the area or call for help, depending on the severity of the leak and the context of the incident. Attempting to fix the leak before shutting off the fuel could lead to a more dangerous situation, making the immediate action of shutting off the fuel paramount.