The Invicta Virtuosi driver contracted a broken wing before spinning out at Massenet while running in fourth.
Upon his rear impact with the wall, his car burst into flames and prompted a red flag with half the road blocked.
Zane Maloney, who had been running behind Doohan for Rodin Carlin, had a near-miss but took evasive action.
Speaking after the race, the Alpine Academy member said he initially thought he had gotten away with his contact with the wall at Swimming Pool, hence not pitting immediately after.
He told Autosport: "I just made a mistake, clearly. I don't really remember it 100%, but I know that I went into the wall here, then exited the second part of Swimming Pool and I felt that I just did the front right.
"I went to the last few turns and went on the main straight. I tried to weave and I thought maybe I'd gotten away with it, and went through Turn 1 and it was all normal, but clearly I hadn't.
"And yeah, when I got to the top of Massenet, as soon as I had the car loaded, it just completely went on me."
Doohan, son of motorcycle racing legend Mick, said the fact the whole car caught fire was "very worrying" and initially thought it was just the brakes which had set alight.
He also said he was "definitely a bit groggy for a while" after the crash and was "very fortunate" to escape in time, adding: "Initially, I couldn't get my buckle loose.
Source: Autosport