A woman has suffered extensive burns after trying to rescue her dog from a hot spring in Yellowstone National Park, authorities have said.
The woman was pulled out of the water by her father and taken to a regional hospital with "significant thermal burns" across her body.
The 20-year-old woman's dog jumped into the near-boiling water and later died.
Authorities are investigating the incident, the latest in a string of burnings at the park.
In a statement, the US National Park Service said that the woman, a resident of Washington state, exited her vehicle to chase after her dog on 4 October.
She entered a thermal hot spring known as Maiden's Grave Spring to retrieve the dog, which resulted in "significant thermal burns between her shoulders and feet".
The temperature of the water at Maiden's Grave is 200F (93C), according to park officials.
After being pulled out of the hot spring by her father, she was transported to a medical centre in the US state of Idaho.
"The park has learned that the dog, unfortunately, passed away," the statement added.
While the park service did not identify the woman, a GoFundMe campaign started to seek money for her medical bills identified her as Laiha Slayton.
On Instagram, Ms Slayton's sister wrote that she suffered mostly second degree burns during her approximately eight seconds in the scalding water.
"This means that our dad pulled her out insanely fast," Kamilla Slayton wrote. "She's incredibly lucky. Dad saved her life."
Park officials have repeatedly warned visitors to be careful when in hydrothermal areas and remain on boardwalks and trails and to physically control pets at all times. Pets are not allowed in thermal areas.
The incident marks the second significant injury in a Yellowstone thermal zone this year. In September, a 19-year-old woman suffered extensive second and third-degree burns to 5% of her body at Old Faithful, Yellowstone's most popular geyser.
In 2020, a three-year-old suffered injuries after running off a trail and falling "into a small thermal feature".
Yellowstone's safety website notes that more than 20 people have died from burns suffered in the park's hot springs.
Hot springs have killed or injured more visitors at Yellowstone than any other natural feature.