Oil being ruptured is usally black when it gets burned from an exhuast manifold.
Coolant is usually white when it also does. But to lose power woud indicate an internal leak but it wouldn't smoke under the hood. What did it smell like burned rubber ,sweet smelling ? What did the condition of the engine look like after the smoke cleared? Does the car start at all?
Level of oil,coolant ,tranny?
Try to fill in all the blanks and we might be able to help you track it down a bit.