The harnesses are not difficult to unlatch when you need to get out of them. Even if she were knocked unconscious, another person could unlatch her harness with little effort.
The deputy director said he was holding her hand in the water and at some point she let go. So she was conscious, and it was also noted that she had her life jacket on. The deputy director was able to get out safely and IIRC one of the reports said he was not hospitalized afterwards either.