Cade Edmond Siemers, 48, told park rangers that he went out walking without a flashlight, and ended up tripping and falling, landing in the thermal water, NBC News reports. Siemers, a U.S. citizen living in India, was seriously burned all over his body, and is now receiving treatment at a burn center in Idaho.

The National Park Service said on Monday that rangers discovered Siemers' hat and shoe and a beer can by Old Faithful, as well as footprints going to and from the geyser. There are signs all around the park telling people to be careful and take notice of their surroundings, and rangers are now looking to see if any damage was done to the geyser cone. Once the investigation is complete, the results will be "forwarded to the United States Attorney's Office for prosecutorial review," the National Park Service said.