Authorities are actively seeking a motorcyclist who vanished after a dramatic explosion in Adelaide, an event captured on CCTV.

Police are concerned that the individual may have sustained severe injuries and is in urgent need of medical attention following the incident on South Road at St Mary’s.

Video footage reveals the motorcycle exiting the Southern Expressway, at which point the rider appears to lose control.

The bike then skidded across South Road, narrowly avoiding a stobie pole, before colliding with a guardrail, which triggered a massive explosion.

Onlookers recounted the ferocity of the fire.

“It was incredibly dangerous, just a ball of flames—I was in disbelief,” remarked Dan Peters.

Despite the force of the impact, the rider was observed getting to their feet and leaving the area. 

Subsequent observations indicated the rider returned to the scene, wearing a black hoodie, and appeared to assess the damage. 

Witnesses reported the rider then sought a lift from a passing motorist in a white car. 

“Some random guy walked in with his hoodie on, seemed to pick something off the bike then legged it,” said Peters.

Police investigations have revealed the motorbike was stolen approximately 400 kilometres away in Whyalla nearly six months ago.

It was also discovered that the motorbike was displaying stolen number plates.

The investigation into the circumstances surrounding the incident is ongoing.