There isn't a single, easily accessible "emergency fuel shut-off switch" like you might find on some other vehicles on a 1995 Cadillac STS. Fuel delivery is controlled by the electronic fuel injection system, and there's no readily available manual override. Disconnecting the battery is the closest equivalent to shutting off fuel flow in an emergency. This will stop the engine from running.
If you have a fuel leak, do not attempt to locate a non-existent switch. Instead, turn off the ignition, evacuate the vehicle, and call for emergency assistance.
