A man is presumed dead after walking off the boardwalk and falling into a hot spring at Yellowstone National Park's Norris Geyser Basin. The spot is considered the oldest and hottest of the park's thermal areas. Photo by IrinaK/Shutterstock

BILLINGS, Mont., June 8 (UPI) -- A man is presumed dead after falling into the hottest hot spring at Yellowstone National Park, officials said late Tuesday.

Witnesses saw a man in his early 20s leave the boardwalk at Norris Geyser Basin and fall into the hot spring seconds later. Rangers are treating the incident as a death and have not found the man's body, park officials said in a statement.


Norris Geyser Basin remains closed.

"At this time, rangers are treating this incident as a probable fatality because the victim has not been located," Jody Lyle, a park spokeswoman said.

The man was considered to be about 225 yards from the end of the boardwalk when he fell in. Because of the high temperatures, rangers are having to be extremely careful in their search for the body, park officials said.

The Norris Geyser Basin is considered the hottest, oldest and most volatile of Yellowstone's thermal areas, according to the park's website. The highest temperature in a Yellowstone geothermal area was recorded there, and most of the spot has features over the boiling point.

A 13-year-old boy was burned on his foot and ankle on Saturday after falling into nearby Upper Geyser Basin.