The search is on for 3 missing climbers who have disappeared on K2, the deadliest mountain in the world

• Three climbers have gone missing on K2, the world's second-highest mountain.
• Ali Sadpara, John Snorri, and Juan Pablo Mohr were last seen early Friday morning.
• Sadpara's son said he believes his father and climbing partners are dead.

Ali Sadpara of Pakistan, along with John Snorri of Iceland and Juan Pablo Mohr of Chile, disappeared during a climb of K2 over the weekend.

K2 is the world's second-highest mountain but is considered the deadliest and most difficult to climb. Around one in five who attempt it die in the process.

"The base camp received no signals from Sadpara and his foreign companions after 8,000 meters," Karrar Haideri of the Pakistan Alpine Club told the South China Morning Post. "A search is on and let's pray for their safe return home."

A post shared by Muhammad Ali Sadpara (@muhammadalisadpara)

Sadpara is a well-known and celebrated climber who has successfully climbed eight of the world's highest mountains. Both Snorri and Mohr are also considered experienced and skilled climbers.

Sadpara's son Sajid had also been on the climb with the three but turned back early after experiencing a technical problem with his oxygen tank. He told reporters that he last saw his father early on Friday morning and doubted that his father and the other climbers were still alive.

"Rescue operations now only make sense if they are carried out to bring back his body," Sadpara said. "Otherwise, for the chance for anyone to survive at 8,000 meters [after being missing for] two to three days are next to none."

Helicopters have been searching for the climbers for the past several days, but because of the severe weather and elevation, rescuers are only able to go out for an hour at a time.

A member of the group's support team posted on John Snorri's Instagram that he believed the team's GPS tracker had run out of batteries.

"The garmin tracker is out of battery. I am talking with the teams chef and base camp manager Haris," he wrote. "He has radio connections with the team. We have decided not bother them and wait until they will contact Haris. We are not listening to other news, we are the only source to the team. We have strong believe that they will summit soon."

Snorri was last spotted on his GPS on the morning of February 5 at an altitude of 25,000 feet.

K2 is located on the China-Pakistan border and has an elevation of more than 28,000 feet. It's around 800 feet shorter than Mt. Everest but is considered one of the most dangerous climbs in the world. Because it is located further north than Everest, weather conditions on the peak can be much more extreme. Temperatures can drop to as low as -76 degrees Fahrenheit and winds can whip up to a speed of 125 mph or more.

A post shared by John Snorri (@john.snorri)

On August 1, 2008, a group of 25 climbers and Sherpas from seven countries were beginning the long, difficult descent from the summit when a series of tragedies led to the deaths of 11 climbers in a 24-hour period.

Sadpara, Snorri, and Mohr had been at base camp and waited more than a month to climb K2. Weather conditions prevented the group from beginning their trek until February 3.