Must have been a sudden plunge for no skydivers to have jumped. I know they were probably not prepared to jump but hey.......
The plane crashed near the field, which makes me think it happened during takeoff or very shortly afterward. There might well have been insufficient time and altitude for anyone to get out and open a chute.
In my (not very extensive) skydiving experience, the ride up was the part when I worried most. It was always a relief to get out of the plane.
See 15.