Eight people were killed on the California side of Lake Tahoe when a sudden, violent storm struck without warning - unleashing 10-foot waves, pounding hail, and torrential rain that capsized their boat.

Ten boaters aboard a 27-foot gold Chris-Craft vessel set out to Lake Tahoe Saturday afternoon, eager to enjoy a sun-drenched day on the water for a birthday celebration, as reported by ABC 7 News.

But the day turned deadly when an unexpected, powerful storm exploded over the lake, capsizing their boat without warning - an apocalyptic scene captured in stomach-churning video footage.

Tragically, eight people were killed in the disaster: Paula Bozinovich, 71, Terry Pickles, 73, Joshua Antony Pickles, 37, Peter Bayes, 72, Timothy O'Leary, 71, Theresa Giullari, 66, James Guck, 69 and Stephen Lindsay, 63.

'It's the worst situation I've seen on the lake,' South Lake Tahoe Mayor Tamara Wallace told the Los Angeles Times, describing it as an 'unspeakable tragedy.'