The flight was in level cruise and 3 of the 4 jumpers were positioned on the step ready to jump. The reserve chute on one of the jumpers accidently deployed and was sucked forward and over the right wing leading edge. The jumper was pulled forward and over the wing, and in the process, hit his head on the wing leading edge and substantially damaged the internal wing structure. As the jumper’s chute deployed over the wing, the aircraft was rolled inverted. The other jumpers jumped and parachuted to the ground safely.