A 26-year-old Boulder woman died after free-solo climbing on the Four Aces of Blitzen Ridge in Rocky Mountain National Park and falling about 500 feet, park officials said.

Her 27-year-old climbing partner, who notified rangers via cell phone of her fall on Sunday, was uninjured and rescued using a Colorado Air National Guard helicopter and hoist.

A park search and rescue team hiked to the area, above Ypsilon Lake, to assist with the recovery of the body, park officials announced in a news release. The woman wasn’t identified.

The Blitzen ridge on Ypsilon Mountain is located on the east side of the park. Free-solo means climbing without a rope for protection.