Images have emerged showing a fan attending the car that had backed into the wall at The Chase during Practice 2.
The spectator was carrying a fire extinguisher believed to have been picked up from a marshal post.
Social media reports claimed the fan was first to arrive at the #540 entry driven by Tim Pappas before marshals and medical crews followed to help extricate the driver.
Organisers have confirmed that a full review into the incident will be conducted.
“CAMS and Supercars Events, the promoter of the Bathurst 12 Hour, are investigating the incident and subsequent response to the accident involving car #540 this morning,” read a statement issued to media including Speedcafe.com.
“As with any motor sport incident, CAMS will conduct a full investigation once all relevant information has been gathered.
“Supercars Events will assist in the review process, in consultation with track management.”
Pappas was conscious following the impact and has since been transferred to the circuit's medical centre before being taken to hospital.
The entry has been withdrawn from the race.
UPDATE: Initially believed to be a single fan jumping the fence to extinguish the fire in the Black Swan Racing Porsche, images obtained by Speedcafe.com show at least two people entered the circuit.