The pilot reported that before the flight he checked the weather in the area for the balloon flight which indicated light and variable wind conditions about 4-5 knots and no forecasted weather that would adversely affect the flight. At the conclusion of the flight, and as the balloon approached the ground, the wind picked up causing the balloon to descend and the basket lightly touched the ground. After recovery from the unintended landing, the pilot maneuvered to land the balloon. The balloon picked up and gained altitude when there was a sudden 180o wind shift. The ground speed increased, and the balloon started a descent. The pilot used multiple burners but could not arrest the rate of descent. The pilot commanded the passengers to get down and the balloon touched down around 20 mph on an irrigation ditch which tilted the basket. The pilot was ejected from the basket and the balloon drifted back into the air. The pilot yelled to the passengers to pull the red Q-vent line for a fast deflation system to stop the balloon from climbing higher. The balloon started its descent back into the high ground wind, landed and was dragged into a cattle fence. The pilot was not injured. Two passengers were seriously injured, and 13 passengers received minor injuries. The balloon was not damaged. The pilot reported that there were no mechanical malfunctions or failures with the balloon that would have precluded normal operation. A weather study of the area revealed that the weather encountered was not forecasted.