According to E! Online, a gust of wind blew a projection screen into a ferris wheel on the Hannah Montana movie set, injuring a couple of extras. None of the injuries were serious.
Neither Miley or Billy Ray were on the set when the accident occured.
The official statement from Disney reads, in part:
“During a break in the filming of Hannah Montana: The Movie, a minor accident occurred involving a piece of production equipment. Fortunately, there were only a few minor injuries. Medical personnel have treated the extras and crew involved. None of the cast was on the set. Filming has resumed.”
(via Disney Society)