KHAPLU (AFP) — Two elite Japanese mountain climbers fell from Pakistan’s K2, officials said Sunday following an attempt at a helicopter rescue that spotted the motionless pair but was forced to turn back.

Veteran mountaineers Kazuya Hiraide and Kenro Nakajima were attempting an ascent of the jagged western face of the world’s second highest mountain, using an expert climbing style prioritizing speed and relying on minimal fixed ropes.

But on Saturday “they fell from a height of 7,500 meters,” Alpine Club of Pakistan Secretary Karrar Haidri said in a statement.

“A helicopter rescue was attempted, however the heli could not land,” said Wali Ullah Falahi, the deputy commissioner for Shigar district, which encompasses the 8,611-meter K2.

“Upon close inspection, the bodies of the two climbers were spotted, and it was determined that there was no movement. The heli then turned back,” he told Agence France-Presse.

No organization, as yet, has confirmed the pair are dead.

Ishii Sports — a Japanese outdoor goods brand sponsoring the pair — said the high altitude and steep slope forced the helicopter to abort its landing.

“The pilot said the two men can be seen, but their status was unclear,” the firm said in a statement. “We are currently reviewing how we will rescue them.”

Rescue attempts are extremely risky on K2, even on the southeastern ridge, which is the most common route climbers take to the top.