The first happened on the main straight when Shae Davies was pitched into a roll after his truck nosedived off a jump.
Davies emerged from the wreck unharmed, the session red-flagged as the crashed truck was recovered.
That was followed by a brief spell of green running before Matt Mingay had a similarly awkward landing off a jump at the second-last corner and was tipped into a violent roll.
The wild crash saw the fuel cell ripped from the truck and left burning on the side of the track, while several barriers required significant repair, causing a lengthy delay in the schedule.
The action-packed start has prompted doubts over the ongoing participation of the trucks in Adelaide.
Motorsport Australia has confirmed to Speedcafe that it is currently investigating the crashes.
The trucks are due back on track at 11:50pm tomorrow for qualifying.
