The balloon pilot reported that, after encountering a thermal en route, he decided to land the balloon in a hayfield surrounded by a wooded area. The balloon was "driven down into the tree branches" and, when over the hayfield, the balloon descended and bounced hard. The balloon bounced about 10 ft as he deflated the envelope. The balloon landed hard once more and deflated. One passenger received serious injuries.
The pilot reported that there were no preaccident mechanical failures or malfunctions with the balloon that would have precluded normal operation.