CAM sensor broken and pieces of metal in the CAM

1997 Ford Taurus - while driving down the highway the service engine light came on and some hesitation was experienced. A squeal came from the engine occasional that day. Took it to a repair shop and was told that the computer diagnostic test indicated a bad cam sensor. Later that day I was told that the cam sensor was found broken with pieces of metal missing. They said that the metal is now in the cam and the cam will need to be replaced or get rid of the car. Has anyone ever experienced a cam sensor breaking on it's own, or does a cam sensor go bad, and it is broken in the process of removing it?