On October 10, 2018, about 0943 mountain daylight time, a Balloon Works Firefly 7-15 balloon, N7252H, experienced a hard landing in a field about 4 miles west of Placitas, New Mexico. The pilot was not injured and the two passengers sustained serious injuries. The balloon was not damaged. The balloon was registered to and operated by the pilot under the provisions of Title 14 Code of Federal Regulations Part 91, as a personal flight. Visual meteorological conditions prevailed, and no flight plan was filed for the flight that departed the Albuquerque Balloon Fiesta, Albuquerque, New Mexico, about 0851. The flight's destination was a landing area that was near the accident site. According to the pilot, as he descended and maneuvered the balloon to check the wind for landing, he inadvertently collided with a hill that was at a higher elevation than what he expected. He reported that the balloon's airspeed was between 15 to 20 mph during the collision. The balloon impacted the terrain firmly and both passengers sustained a broken ankle. The pilot subsequently landed the balloon uneventfully. The forecast wind at Albuquerque, located 17 nautical miles from the accident site, was 4 knots, while the wind reported by the pilot was between 6 to 8 knots. The pilot reported no mechanical failure or malfunction with the balloon that would have precluded normal operation.