A spokesman for the Sinaloa state prosecutors' office says the six-passenger Cessna crashed near the city of Guasave.
Guadalupe Martinez said today the plane's wreckage and the victims were burned beyond recognition, as were the plane's registration number.
Martinez said the crash occurred around midday yesterday on a flight that apparently originated in the neighboring state of Chihuahua.
Both states are known for drug cartel activity, and traffickers are known to use small planes.
But the mountainous terrain of Chihuahua also obliges many regular citizens to travel in small planes.