A Japanese climber died Tuesday morning on Denali after an "unknown medical illness," Denali National Park and Preserve officials said Wednesday.
Park spokeswoman Maureen Gualtieri said in a statement that the deceased man, 66-year-old Masayuki Ikeda, hailed from Toride, Japan.
"(Ikeda) was a member of a four-person climbing team making a bid for the summit of Denali the night of June 13 when he fell ill," Gualtieri wrote.
Ikeda was encountered between 18,400 feet and 19,000 feet by another group descending the 20,310-foot peak's West Buttress route the next morning, at 2:30 a.m. Tuesday.
"At that point, (Ikeda) had an altered mental status and was non-ambulatory," Gualtieri wrote.
The climbers descended to the mountain's 17,200-foot high camp, where they placed a distress call to park staff using a satellite phone at about 5:30 a.m. By 7:45 a.m., a high-altitude park helicopter launched to pick up Ikeda.
"After an initial reconnaissance flight to the upper mountain, the helicopter pilot flew back to the 18,400-foot elevation with a short-haul rescue basket," Gualtieri wrote. "The teammates loaded the patient into the basket, and the climber was short-hauled down to the 14,200-foot camp."
Ikeda didn't have a pulse at that point, and was moved into the helicopter. Two Alaska Air National Guard pararescuemen began trying to resuscitate him during a flight to the mountain's 7,200-foot Kahiltna Basecamp, where he was declared dead at 9:40 a.m.
Gualtieri said rangers hadn't yet spoken with Ikeda's party or the group that attempted the initial rescue. Both groups were at the mountain's 17,200-foot camp Wednesday morning but expected to descend to the 14,200-foot camp, where rangers were present.
"We did not have rangers high on the mountain at the time of the events," Gualtieri said. "Most of what we know comes from limited radio traffic at the time."
Gualtieri said Ikeda's body had been transferred to Talkeetna and was being sent to the State Medical Examiner Office to determine a cause of death. There weren't any obvious signs Tuesday pointing to a possible cause.
"There's nothing we know of that would attribute it to anything traumatic," Gualtieri said. "It could be altitude-related, it could be cardiac, it could be any number of things — we may be able to get more on that when we can speak to the climbing party in question."