Both Randle and Heimgartner walked away from the wreckage, and were assessed by medical staff before being sent to hospital for precautionary scans.
The race was immediately suspended, with cars ordered to pit lane due to debris on the pit straight.
When racing resumed van Gisbergen continued his dominance and cruised to his second victory of the weekend, his 13th of 2022 and 67th of his career.
Van Gisbergen didn't get a great start when driving resumed, but when the opportunity presented itself to take over, he didn't miss it.
"From the restart, I didn't get a good start again, but then we had an awesome race back through," he said. "I couldn't believe it when those guys pitted. I got clear air and just pushed on. We were planning to do the undercut then, but they pitted and we got clear air."
In winning Sunday's second race, the third of the weekend, van Gisbergen gave Holden an unassailable lead in the Champion Manufacturer standings, Red Bull Ampol Racing opened up a 121-point lead in the teams' championship.
The 2022 season will resume at the Penrite Oil Sandown SuperSprint next month.