A 37-year-old Michigan woman died Monday from medical complications while hiking in one of the United States’ least visited national parks: Isle Royale.

National Park Service officials announced Wednesday that the Battle Creek woman died late Monday afternoon while hiking near Lake LeSage in the national park. She was hiking with her partner when she experienced “sudden medical complications,” a news release said.

As her condition worsened, she eventually became unable to walk, lost consciousness and stopped breathing, officials said. CPR was initiated, but attempts to revive her were unsuccessful.

Other backpackers in the area contacted Michigan State Police via a delayed 911 text message. That information was then relayed to a National Park Service dispatch center.

“Park rangers/emergency medical personnel found the group Monday evening and remained with them,” the press release states. “Early Tuesday morning, a team of Isle Royale personnel responded to transport the group from a remote location.”

The investigation into her death is ongoing.

“The community of Isle Royale extends its sincere condolences to the family and friends of the deceased,” the press release said.