Two people were found in critical condition on Monday at a mountain in Northern California. A third person was killed by “tough” conditions, according to authorities and a witness.

According to the Siskiyou County Sheriff’s Office, the incident that resulted in the death of the victim was reported on Monday morning at Mount Shasta near the Oregon border.

According to the sheriff’s office, the person was declared dead before rescue efforts could be launched.

According to the sheriff’s office, another victim was left in critical condition. A third victim sustained a broken ankle.

According to the sheriff’s office, a fourth person was taken into critical condition following a second incident that occurred on Monday afternoon.

A helicopter crew from California Highway Patrol saved Monday night a fifth person who had previously been reported missing and hurt. Her condition was not immediately known.

The death or injuries were not explained by the sheriff’s office. The sheriff’s office described the victims as “climbers”.

Mount Shasta, at more than 14,000 feet is a popular climbing destination in the spring and early part of the summer.

Wallace Casper from Bozeman, Montana described Monday’s treacherous mountain environment in a video posted online by the sheriff’s office. He said that a layer of water ice atop the snowpack made ski navigation impossible.