Snow doesn't like rapid changes. 4ft of snow in such a short time is most definitely rapid change. Unusual even for Tahoe. Vibes to all the people involved. Sad day.
Really crazy amount of snow in such a small period of time, like you say it's even unusual for Tahoe. My sister posted these pics to her FB on that day, they show just how much snow was in the area:
Her driveway after digging her car out:
From the tram at Alpine that day: