Confusion; Situational Awareness
Deviation / Discrepancy - Procedural Other / Unknown
General None Reported / Taken
Aircraft; Human Factors
At 1;500 feet; all skydivers took off their seat belts. Immediately afterwards; the plane rolled over nearly if not 90 degrees and then went into a dive. It fired 3 skydivers reserve parachutes inside the plane. We landed and exited without further incident. They [skydiving company] had a dismissive attitude about the event; but I believe it needs [to be] addressed. If they had hit another plane; there would have been deaths and had the door been open; which many times it is; we would've all been sucked out in a tangled pile. I hope that this is the correct way of reporting the incident as I couldn't find another source. Thank you for your time.
A skydiver reported that the jump aircraft may have experienced an inflight upset.