Investigators are trying to determine what caused the death of a Disney performer who was injured while performing in a Magic Kingdom show.

A friend says 47-year-old Mark Priest was sword-fighting in "Captain Jack Sparrow's Pirate Tutorial" when he slipped and hit his head on a wall.

A Disney spokeswoman said the company had no idea his injuries were life-threatening. Disney on Monday contacted the sheriff's office and Occupational Safety and Health Administration after hearing Priest died.

Priest's condition was improving, and didn't seem serious immediately after the injury. The actor was able to rush offstage and joked about his condition at the hospital.

He was moved out of intensive care Monday, but deteriorated rapidly and died. No official cause of death had been determined.

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The Associated Press contributed to this report.