The incident occurred around lunchtime, local time, while off-piste skiing in an area northwest of Lake Tahoe.
Later in the day, six skiers were found alive in the snow but not yet rescued. Ten people were still missing. The avalanche was triggered by a storm.
"It's especially dangerous in the area right now because the storm is ongoing," said Brandon Schwartz, who works with avalanche forecasting at the Sierra Avalanche Center.
