Mazda Tribute unexpectedly shut off

Without actually seeing the car its hard to say with any certainty but here are a few things you can look at . The fuel filter may be getting plugged and with a sudden drop in rpm it starved the engine for fuel and stalled . There could be an electrical short at work that a bump or bounce like entering a parking lot could trigger. Transmission may not have geared down and stalled out . Did you get a engine light after the event?

if so having the code read could be helpful . hope you find this helpful