Jonathan Goodwin, a daredevil stuntman on the new "America's Got Talent: Extreme" suffered brutal injuries after a stunt he attempted went horribly wrong, and it was so bad people on the set thought he was dead.
Production sources tell TMZ ... Goodwin was suspended 70 feet in the air in a straightjacket hanging by his feet from a wire. Two cars were suspended on either side of him ... swinging back and forth. The stunt was for Goodwin to free himself from the restraints and then fall on an air mattress, and avoid getting crushed by the cars as they swung in the air.