Elisha Brabin, 36, and her children, Leo, 16, Ellis, 8, and Prudence, 7, died after a blaze "spread rapidly" inside a house on Stone Square in Bootle, Merseyside, in the early hours of 22 September.
Following an investigation with Merseyside Police, Merseyside Fire and Rescue Service (MFRS) said the fire was caused by an electrical event linked to a lithium-ion battery, which are used in e-bikes and e-scooters.
MFRS said: "This tragedy highlights the very real risks posed by lithium-ion batteries, which we confirmed as the source of the fire."
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