At least one American climber is among the 10 or more dead after an avalanche caused by an earthquake on Mount Everest. Google engineer Dan Fredinburg, who was on Everest as part of the Jagged Globe team, died as a result of head injuries sustained in the avalanche, according to Fredinburg’s sister. She posted the news on Instagram on Saturday afternoon along with a picture of her brother on his account.

The caption reads:

“This is Dan’s little sister Megan. I regret to inform all who loved him that during the avalanche on Everest early this morning our Dan suffered from a major head injury and didn’t make it. We appreciate all of the love that has been sent our way thus far and know his soul and his spirit will live on in so many of us. All our love and thanks to those who shared this life with our favorite hilarious strong willed man. He was and is everything to us. Thank you.”

The news comes one day after Fredinburg, who once dated actress Sophia Bush, posted a picture of himself ice training on the mountain.

“Day 22: Ice training with (climber Michele Battelli) means frequent stops for morning cappuccino, regardless of danger. #Everest2015,” the caption reads.

Fredinburg was an experienced climber, who was on Everest last year when an avalanche struck in April. Bush reportedly tweeted that he and his team emerged from that tragedy okay, according to US Weekly.

On Saturday, rescue missions continued on Everest after the avalanche that struck between the Khumbu Icefall left much of the camps buried in feet of ice and snow. Conditions, however, have reportedly made their efforts difficult and other climbers who sustained injuries could be in danger.

Climbers and their teams have been using social media to communicate with their loved ones and update the world on their status on the mountain. One climber described the scene as “horrible,” in a set of two blog posts, but amid the bad news there have been many tweets indicating that the majority on the mountain survived, including American climber Melissa Arnot and her team.

This post will be updated.