Kenneth Keith Kallenbach, one of Howard Stern's longtime Wack Pack members, has died Thursday in a Chester County, Pennsylvania hospital.

The cause of death is uncertain, but Kallenbach apparently contracted pneumonia in jail while being held on attempted child-abduction charges.

The Kidd Chris Show announced that Kallenbach was dead during their morning broadcast.

Kallenbach first appeared on the Howard Stern Show in the early 1990s and became a member of the Wack Pack. Kallenbach then moved on to Sirius and has participated in many of Stern's shows.

Kallenbach, who still does stand-up comedy, has a band, "The Kenneth Keith Kallenbach Band". In addition, Kallenbach writes and directs and acts in his own comedy sketches and also released a sketch comedy DVD nationally called "American Icon".

Kallenbach had recently featured on The Tonight Show with Jay Leno and was also seen impersonating Tom Cruise on Human Giant.