The bodies of eight people known to have died when they were engulfed in a wall of snow cannot be moved because of the storm pummeling the Sierra Nevada mountain range -- and the risk of yet more avalanches.

"Due to hazardous weather conditions, avalanche victims cannot be safely extracted off the mountain today," the Nevada County Sheriff's office said on Facebook.

"Recovery efforts are expected to carry into the weekend."

Six people survived Tuesday's tragedy, one of the deadliest avalanches in modern US history.

The group -- four guides and 11 paying clients -- was on their third day of a backcountry skiing trip on the 9,109-foot (2,776-meter) Castle Peak in the Lake Tahoe region of northern California, an area popular with mountain enthusiasts.

Late Thursday, in a statement reported by US media, families of six of the victims identified them as women who were "mothers, wives and friends, all of whom connected through the love of the outdoors."

"They were passionate, skilled skiers who cherished time together in the mountains," the families' statement said, adding "we have many unanswered questions."

The statement also noted the women were "experienced backcountry skiers" who were "fully equipped with avalanche safety equipment."

The six who survived -- five clients and a guide -- managed to call for help shortly after disaster struck, but white-out conditions and the risk of further snow slides meant rescue teams could not reach them for several hours.

Two had to be helped down and needed hospitalization.

- 'Enormous tragedy' -

The US Forest Service said Thursday all lands it manages in the area will be shuttered for the next few weeks to help in the recovery operation.

"Due to the current instability of the snowpack and need to prioritize first responder access to the area, members of the public are prohibited from entering the closure area during search and rescue operations," a statement said.

"In order to continue recovery operations, emergency personnel will need to use snow machines, aircraft, various other heavy equipment and possibly explosives to mitigate further environmental hazards to the safety of first responders conducting recovery efforts."

The closure order will remain in effect until March 15.

In the aftermath of the accident, questions have been asked about why skiers were out on the mountain in such difficult conditions, with several feet of snow falling in a short period and experts warning of the risk of avalanches.

Expedition organizers Blackbird Mountain Guides on Wednesday said all staff in the group were professionally trained, and urged people to avoid speculating about the circumstances.

"This was an enormous tragedy, and the saddest event our team has ever experienced. In addition to mourning the loss of six clients, we also mourn the loss of three highly experienced members of our guide team," company founder Zeb Blais said.

"Guides in the field are in communication with senior guides at our base, to discuss conditions and routing based upon conditions.

"There is still a lot that we're learning about what happened. It's too soon to draw conclusions, but investigations are underway."