Check out these photos, but be warned they're extremely graphic. The story is that a guy was working in an excavator laying a pipeline in the amazon and the excavator fell into the river. The driver punched out the glass to escape the water, but cut his hand. The resulting blood attracted piranhas, and with know where to escape, the driver was eaten alive.

WARNING: EXTREMELY GRAPHIC PHOTOS! http://www.scribd.com/doc/7573872/Piranhas