LONDON — Two Americans are among eight climbers who went missing while attempting to scale an unconquered peak in the remote Indian Himalayas, according to his family.

Anthony Sudekum, 63, a medical doctor from Defiance, Missouri, was part of a group that disappeared after setting off to attempt an unnamed peak in the Nanda Devi region of the mountain range, according to his daughter Lucy Sudekum.

Anthony Sudekum, second left, is missing in the Indian Himalayas.

The U.S. State Department said Sunday that it was aware of reports that two American citizens were missing in India. The second missing American is named Ronald Beimel, officials told NBC News on Monday.

The alarm was raised early Friday but it remains unclear what happened to the group. It appears that an avalanche may have happened on or very near the route that the climbers were due to take to the 21,000-feet summit, the company added.

The group was on an expedition to Nanda Devi East but they went on an acclimatization climb on an unnamed and unclimbed Peak, according to the British Association of Mountain Guides.

The group was lead by Martin Moran, the founder of a Scottish adventuring company, Mountain Moran. A statement posted on the website said: "We are deeply saddened by the tragic events unfolding in the Nanda Devi region of the Indian Himalaya.

"As a family, we share the same emotions that all next of kin are experiencing in not knowing the whereabouts or wellbeing of those closest to us."

While weather conditions were hampering search efforts, Lucy Sudekum said she and her family were hopeful that her father would be found alive. “Our hope and optimism in this dark moment is buoyed by the knowledge that our dad was a highly experienced climber and outdoorsman and an accomplished medical doctor well trained in emergency medical care,” she said in a statement.

If the climbers had been caught up in an avalanche it would be difficult to search for them in the current conditions, she said. “There are countless stories in mountaineering history of avalanche survivors, presumed dead, turning up alive days later in an unexpected location. That is our hope and we are holding onto that now,” she added.

The alarm was raised when another British mountain guide, who was leading a separate trekking group as part of the same expedition, was informed that the climbers had not returned to base camp as expected, according the company.

He then immediately went on the mountain to search for the missing mountaineers, the company said in a statement. “We have been informed by the Indian Mountaineering Federation that an air search by helicopter has revealed the scale of the avalanche but no sign of the climbers,” it added.

The Indian air force has deployed two aircraft to look for the missing climbers, according to air force spokesperson, Group Captain Anupam Banerjee.

The group's disappearance comes amid this season's high death toll on Mount Everest. Inexperienced climbers and overcrowding on the world's highest mountain are being blamed for the deaths, with the toll reaching at least 11 last month.