A personal mobility device (PMD) left to charge in an Ang Mo Kio flat yesterday exploded in the afternoon, according to an eyewitness, before a fire destroyed the flat and damaged two neighbouring units.

The e-scooter belonged to the fiance of the woman living in the rental flat. He left the device to charge in the kitchen before they both left for work.

Some time between 2pm and 3pm, the woman's older brothers, Mr Mohamad Fazir, 30, and Mr Mohamad Fazrim 26, who were in the flat at the time, heard a loud explosion. Mr Fazir, who saw the e-scooter burst into flames, woke his brother, who was taking a nap in the living room, and they both rushed out of the front door.

"I saw the fire in front of my face and it spread so quickly," Mr Fazir told Yio Chu Kang Citizens Consultative Committee (CCC) chairman Tung Yui Fai when he visited the victims at 7pm.

The Singapore Civil Defence Force (SCDF) said in a Facebook post that it responded to a fire at a fourth-floor unit in Block 224 Ang Mo Kio Avenue 1 at about 3pm.

The fire was raging when the SCDF arrived and one adult and three children were rescued from the unit next to the flat. Around 60 people from the block were evacuated by SCDF and police officers.

A video on YouTube showed plumes of smoke billowing out from the fourth-floor corridor as the fire engulfed the flat. The fire was put out with one water jet.

"Preliminary investigations into the cause of the fire indicate it was from a personal mobility device placed in the kitchen," SCDF said.

This is the fourth fire breaking out in Housing Board flats this month, and the second involving PMDs in less than a week, putting PMD-related fires in the spotlight.

A 40-year-old man who was rescued from a burning Bukit Batok flat last Thursday died in hospital. The fire was linked to three burnt personal mobility devices in the unit, according to preliminary investigations by the SCDF.

The number of such fires has been on the rise, with 74 PMD-related fires reported last year, a 51 per cent spike from 2017, according to statistics from the SCDF.

Ang Mo Kio GRC MP Koh Poh Koon, who visited the block, told reporters that the affected family would be housed temporarily in a flat on the second floor of the block.

When The Straits Times arrived at the scene at 5.40pm yesterday, Mr Fazir's family and their relatives were moving their mattresses and any household items they could salvage into the one-room flat.

The fiance of Mr Fazir's sister, said: "It is strange because I have had this e-scooter for two years." Both of them did not want to be named.

Mr Fazir lived in the flat with his parents, two of his brothers and his sister.

His sister-in-law, who also declined to be named, said the siblings used to work as food delivery riders and had their PMDs in the flat until they switched jobs about a year ago.

She said Mr Fazir's mother, who was at the market when the fire broke out, would always unplug the PMDs once they were fully charged. She added: "It is just unfortunate that the e-scooter exploded in the house today, when the previous PMDs were fine."

The exterior of the two units next to the burnt flat was charred and the fire destroyed the electrical wires of one of the units, causing a power outage in the unit.

The flat's tenant, who wanted to be known only as Mr Muhammad, said his wife and children, all under the age of six, heard the explosion and huddled in a room.