The 2000 Ford Explorer doesn't have a readily accessible fuel shutoff valve like some older vehicles. There's no easily reachable lever or switch. To stop the fuel flow, you'd need to disconnect the fuel pump relay or fuse. The location of the relay or fuse will depend on the specific engine type (you'll need to check your owner's manual).
Important Safety Note: Disconnecting the fuel pump relay or fuse should only be done if there is a genuine safety concern such as a fire or fuel leak. Improperly handling the fuel system can be dangerous. If you are unsure about where to find the relay/fuse or how to safely disconnect it, consult a qualified mechanic.