An exploding lithium-ion battery sparked a fire that killed two people in what firefighters believe are the first deaths linked to a battery fire in NSW.
Emergency services were called to the building at Teralba in Newcastle about 4am on Thursday after reports of a fire.
Fire and Rescue NSW crews managed to extinguish the blaze but not before the building had been severely damaged.
Police found a body during an initial search of the townhouse.
As searches continued on Friday, a second body was found.
Two other people escaped the blaze.
Investigations were paused to assess the building's structure but firefighters have since identified the cause.
A compromised battery went into "thermal runaway", overheating and emitting toxic gases before exploding in flames, Fire and Rescue NSW said in a statement on Tuesday.
"The tragedies mark what FRNSW regards as the first deaths in NSW due to a lithium-ion battery-related fire," the agency said.
Commissioner Jeremy Fewtrell said the fatal case appeared to confirm what firefighters had been "fearing for a while" after a rise in battery fires.
He warned the dangers of a battery going into thermal runaway were immediate, creating intense, volatile fires that were hard to put out.
Overheating batteries have already been linked to 44 fires in NSW in 2024 - a rate of about five per week - while 269 blazes were connected to batteries in 2023.
People are advised not to leave devices charging while they sleep, near flammable materials or exits to a home.
Police are working to identify the two people killed in the townhouse blaze after their bodies were recovered from the ruins.
A report will be prepared for the coroner to determine an official cause of death.
