According to a report from Thanh Tri District Police Department, the fire broke out at around 5.40pm at a house which was also used to store scrap metal in Hong Ha Urban Area.

"We soon arrived at the site and managed to control the fire after 20 minutes," the department said. "However, the fire spread so fast and quickly burnt down the 30-square-metre house with a large amount of scrap metal inside. There were four family members inside and three of them, including a 31-year-old woman and her two sons aged 11 and five, were found dead while the 35-year-old husband suffered serious burns."

A witness said that he heard a loud explosion coming from the house and came out to see the large fire spreading very fast with smoke rising up to tens of metres high.

Initial investigations showed that the fire broke out when the couples, who traded scrap metal, used a device to squeeze a hair spray bottle when it suddenly exploded and spread to a nearby gas cylinder.

Police are further investigating the cause of the incident.