How did Charli Damelio die?

16 year old Charli Damelio was found in a car crash, with her mother and father Heidi and Marc Damelio. With only Heidi and Marc surviving. Leaving 16 year old Charli Dead. How did this happen? The family were in a car in the Bahamas, then crashing into the ocean. Leaving Charli to die from drowning.