A video of last Sunday's fatal bus accident at Dairy Farm Road has emerged on citizen journalism website Stomp.

The video shows the SMRT bus mounting a grass patch and moving into an oncoming vehicle's lane, narrowly missing it. The bus later overturned.

A 19-year-old male bus passenger was killed while the driver and the only other passenger on board bus number 700A were sent to hospital for treatment.

The video was contributed by a Stomper known only as Chin Tian, who told the website: "I witnessed the SMRT bus accident at Dairy Farm Road during my driving, at around 8am plus.

"My car was nearly hit by the SMRT bus. From the video shown, the SMRT bus had been going at a speed of at least 100km/h from BKE Exit 2, all the way down till it hit the kerb, lost control, skidded into the other lane, and crashed.

"I heard a long bang too."

The 39-year-old driver, a Chinese national, said he had stepped on the brakes, but the bus "suddenly went crazy" and its speed kept climbing despite four attempts to slow it down.