A "catastrophic" pipe failure led to a gas leak which caused a fatal house explosion, it has been confirmed.
A cooker spark ignited the blast, which destroyed one house and badly damaged another in Allington Drive, Birstall, on Monday morning.
Janet Jasper died in hospital, while two men were also injured in the blast. One remains in hospital.
Investigators found "a catastrophic failure of an internal gas pipe joint" was the source of the leak.
The explosion also damaged nearby houses, with a "handful" of families sent to temporary accommodation.
In a statement, the fire service said: "The joint investigation has determined that there will be no criminal investigation.
"A forensic investigation is now underway by the Health and Safety Executive to identify what caused the failure of the internal gas pipe."
The gas maintenance company Cadent, which supplied the house, said it only had responsibility for pipes up to the gas meter.