JUNEAU, Alaska — Two climbers awaited rescue near the peak of North America's tallest mountain Wednesday, a day after they and a third climber in their team requested help after summiting Denali during the busiest time of the mountaineering season, officials at Denali National Park and Preserve said.

Their condition was not immediately known. The third climber was rescued late Tuesday. All three had listed experience on high-elevation international peaks on their climbing histories, and two had prior history on Denali, park spokesperson Paul Ollig said in an email to The Associated Press.

Park rangers received an SOS message from the three at 1 a.m. Tuesday, indicating the climbers were hypothermic and unable to descend after reaching the 20,310-foot (6,190-meter) summit.

They remained in communication until around 3:30 a.m., when they texted plans to descend to a flat area known as the ''Football Field'' at around 19,600 feet (5,974 meters), the park service said in a statement.

Rangers did not hear back from the climbers after that, and the location of their satellite communication device didn't change. Cloud cover prevented the park's high-altitude helicopter from flying about 50 miles (80 kilometers) from the community of Talkeetna to Denali Tuesday morning, so the park requested help from the Alaska Rescue Coordination Center. The Alaska Air National Guard flew an HC-130J airplane from Joint Base Elmendorf-Richardson in Anchorage to look for the climbers.

Two of the climbers were located between the 19,000- and 20,000-foot (5,791- and 6,096 meter) level of the mountain before noon Tuesday. The third climber was seen by a climbing guide at about 18,600 feet (5,669 meters).

Conditions cleared enough Tuesday evening for the high-altitude helicopter to make another attempt, and it landed at a camp for climbers at 14,200 feet (4,328-meters).

There, National Park Service mountaineering patrol rangers had been treating two climbers from another expedition for frostbite. The helicopter crew evacuated those climbers to Talkeetna.

A third attempt was made Tuesday night to reach the three climbers who sent the distress message. By then, one of them had descended to a 17,200-foot (5,243-meter) high camp and was suffering from severe frostbite and hypothermia, the park said. The climber, who received aid from a guided party until a park service team arrived, was flown off the mountain and later medevaced from Talkeetna.

The park service said an experienced expedition guide on the upper mountain provided aid to the other two climbers, who were at the ''Football Field,'' but the guide was forced to descend to the 17,200-foot (5,243-meter) high camp for safety reasons when clouds moved back in.

Clouds and windy conditions prevented rescuers from reaching the two climbers Wednesday, either by aircraft or ascending the mountain. Park service personnel were waiting for conditions to improve before making further attempts.

Ollig, the park spokesperson, said it was not known how much survival equipment the two climbers have, but said ''it is likely minimal.''

''Typically, on a summit day teams will often go up lighter, with more limited survival gear, so they can move faster,'' he said.

He said while this is ''certainly a dramatic rescue operation, it is not necessarily out of the ordinary.''

There are 506 climbers currently attempting to summit Denali, and the park service said the Memorial Day weekend is the start of the busiest two weeks of the climbing season.

Another 117 climbers have completed their attempts to climb the mountain. Of those, 17 reached the summit.

Denali National Park and Preserve is about 240 miles (386 kilometers) north of Anchorage.

___

Thiessen reported from Anchorage, Alaska.