Monroe police Lt. Charles Abel says the blast Tuesday evening is "being listed as a car fire with an explosion," and he doesn't know whether it was the result of a vehicle malfunction or something else.
Police in the city near the Ohio state line had said earlier Wednesday it was "being investigated as the detonation of a car bomb."
Abel says local, state and federal law enforcement officials are to meet midmorning to discuss the case.
The vehicle's three occupants were listed in serious condition at St. Vincent Medical Center in Toledo, Ohio.
