Air Bag Not Deploy problems of the 2015 BMW X5

My husband was traveling on the highway at night. He stated that the car in from of his was stopped in the middle of the highway. He was unable to stop in time to avoid rear ending the other vehicle. We have a new BMW X5 SUV and he hit a Lexus SUV- both substantial vehicles. Both cars were not drivable following the accident. There is major front end damage- possible the car is totaled. I'm not sure yet. The air bags did not deploy. The impact fractured his sternum. He developed pneumonia 2 days later because of the pain in breathing- the accident was wed. Night but the fracture was not diagnosed. I took him back to the er fri afternoon, when the fracture and subsequent pneumonia was diagnosed. He was admitted to the hospital and is still there. The car was towed to the dealership. They want to take it apart to see what needs to be repaired or if it is totaled. I want to understand why the airbags did not deploy and am afraid if they start taking the car apart I will never know. I was told the NHTSA would help me with an investigation into this. Please help me and let me know what I should do next. Husband won't be released for several days possibly.