You are left without genuine 'scientific' evidence. This does not mean if 500 people saw me walk on water, it couldn't be considered evidence that a supernatural phenomenon occured. (of course, other options should be looked into first. Is it a trick ? is it an as-of-yet unknown natural phenomenon ?)
At what point to do you give up looking for a natural explanation for a phenomena and declare it the product of the supernatural?
More importantly, when has a supernatural explanation ever turned out to be the right answer?