If the roof rafters/trusses/whatever fall inward in a strong wind, it is often because they detached from the walls and/or ridge.
What can happen is that the pressure of the wind, pressing sideways/downwards on a sloped roof and/or pushing against the side wall of the building, rips apart [already-fragile, for whatever reason] connections. This is especially likely to happen if you had rafters (rather than trusses) without collar ties or anything like that, to hold the two different sides of the span together.
The solution, when you rebuild, is to make sure things are REAL STRONGLY stuck together: use hurricane ties (or whatever they are locally called - little galvanized widgets) instead of just toenailing things onto the tops of the walls; use 1/2"+ plywood gussets to build trusses, not those little rectangular metal plates with a gazillion holes to nail into; use collar ties and that sort of bracing wherever possible/necessary, to keep things from pushing together or pulling apart. Make sure your nails are long enough, and good quality galvanized (rusted-through plain steel nails, or too-short nails, tend to lead to things coming apart in time). And make sure the building's walls are braced diagonally, especially if you use plank siding rather than plywood as the skin of the building but it's worth doing even with a plywood sheathed building IMO -- the less the building wants to flex, the better off you are.
(It is also possible for structural members to just collapse in a strong wind due to utter rot, that is to say break right in the middle of a punky-rotten rafter... but that's not real common IME and you generally know it's coming because of the general state of the building.)
Best of luck,
Pat
