Terrible news, not sure of the ins and outs of what safety gear they had, but there is only so much a car can take from a side impact...
That being said, the car should be sufficiently equiped as far as safety goes, respective of what is being asked of the car.
Case in point, if anyone saw this video doing the rounds on Facebook this weekend, the guy lost it at around 200mph and the car rolled.
Given the speed, imo, he should of had a minimum of a full cage, seats, harnesses etc.
The half cage he had just about saved them from being crushed;
https://www.youtube.com/watch?v=beuFXAn5J10