Rachel Blackman was oblivious to the tragedy that killed her 22-year-old daughter until her son screamed: "Mum, Charlotte's under there!"
The landslide in Burton Bradstock, Dorset, on Tuesday dumped 400 tons of rock onto the beach, but nobody nearby thought anyone had been hurt until 12-year-old Mitchell Blackman told his mum that his older sister was trapped beneath the 35ft mound.
Witness Marianne Garner, 44, said: "Nobody had run to help because I don't think anyone realised what had happened.
"Then one of the boys came back screaming, 'Mum, Charlotte's under there'. She got up and rushed over."
Charlotte's dad Kevin, of Heanor, Derbys, and boyfriend Matt Carnell spent 20 minutes frantically trying to dig the autism charity volunteer free until a second landslide stopped them.
Emergency workers finally recovered her body at 9.30pm. Onlookers raised concerns that rubble wasn't cleared more quickly because of health and safety concerns.
One man said: "It seems strange that they had all the gear but had to wait for a geology expert until they could do anything. How many people would've been removed from rubble in the Blitz if there was health and safety back then?"
What a terrible tragedy.