Vehicle fires are usually caused by overheating or electrical problems but explosions are rare, said safety experts. On Sunday, a TransCab taxi that operated on Compressed Natural Gas (CNG) and petrol caught fire and exploded at Commonwealth Avenue opposite Buona Vista MRT station while firefighters were fighting the blaze. The taxi had been involved in an accident with another car at about 2:15pm and caught fire soon after.

While the incident is still under investigation, experts said more can be done to stop vehicle fires. There were more cases last year - 236, compared with 199 in 2015. According to the Singapore Civil Defence Force (SCDF), most of these fires happened when vehicles were travelling on the road.

Road safety expert Gerard Pereira, an Operations Manager at Singapore Safety Driving Centre, said he has noticed more vehicle fires over the last few years. "Usually the fire starts in the electrical components and spreads to the other parts, like the petrol or gas tank, which have flammable substances," he explained.

Automobile Association of Singapore President Bernard Tay said drivers should ensure their car is roadworthy before setting off. "Regardless of whether you drive a petrol, diesel or CNG-fuelled vehicle, make sure you send it for regular maintenance and servicing. Also do regular checks of places like the engine and petrol tank to ensure there are no dents.

"If drivers notice oil dripping from the car or the smell of gas following a road accident, they should move away from the vehicle and call the SCDF, he added. "Also make sure there are no open flames around the area. Even cellphones can set off a spark if you're not careful."

Mr. Pereira said owners should have a portable fire extinguisher in their vehicles. He has kept one in his car for the last four years. "It can at least help mitigate the fire as it is just starting." He said explosions during vehicle fires are rare, but if the vehicle is CNG-fitted, a blast could happen if the tank, which stores the high-pressure gas springs a leak.

"The accident that happened before the fire could have damaged the CNG tank, but we can't say for sure right now," he said, referring to Sunday's incident.

Mr. Koh Bee Soon, Manager of CNG system supplier AutoSoon, said CNG tanks are very hardy and can withstand high heat. "The tanks are bullet-proof, drop-proof and fire-tested, so they're very durable and safe," he said, adding that the explosion could have other sources, like a petrol leak. A TransCab spokesman said investigations into the explosion were ongoing and it was checking its fleet of CNG taxis.

Preliminary investigations by the SCDF and police revealed that the likely cause of the explosion was a road traffic accident that had occurred minutes before. It was the second time a taxi caught fire last month. On 7^th April, an SMRT taxi in Hougang Avenue 3 burst into flames after smoke was seen rising from its bonnet. The driver and his passenger escaped unhurt.