The bodies were seen last week during a helicopter flight by park staff members, park spokeswoman Patti Wold said, adding that officials were trying to determine how to recover them without endangering rescuers.
"Rock and ice fall off the steep wall and an increase in new crevasses in the glacier below make this one of the most hazardous locations in the park," Wold wrote in an email.
Authorities believe the two guides and four climbers fell 3,300 feet during their climb during the last week of May. During the initial search, crews found gear and detected signals from avalanche beacons buried in the snow at the top of Carbon Glacier at 9,500 feet. It's unknown whether a rock fall or avalanche was to blame for the fall.
All six people were experienced climbers who were taking a technical, challenging route to the top of the 14,410-foot (4,392-meter) mountain southeast of Seattle. Known as the Liberty Ridge route, it is not currently being climbed due to unstable conditions caused by increased rock and icefall from warm weather, Wold said.
Last year, about 10,800 people attempted to climb Mount Rainier and only 129 used the Liberty Ridge route, according to park statistics. The vast majority use two other popular routes.
The missing climbers had traveled from as far away as Singapore, Minnesota and New York to ascend the glacial peak. Members of the group were Seattle-based Alpine Ascents International guides Matthew Hegeman and Eitan Green; Erik Britton Kolb, a 34-year-old finance manager at American Express, who had traveled from New York; Uday Marty, a vice president and managing director of Intel in Southeast Asia who was based in Singapore; Seattle mountain climber John Mullally; and Mark Mahaney, of St. Paul, Minnesota.
Wold said that the Chinook flight out of Joint Base Lewis McChord was part of the park's ongoing limited search of the area for the climbers.