1 patient was in critical condition, and rescuers pulled everyone from the water with injuries including head trauma, broken bones and lacerations; three air ambulances responded.
Video from an onlooker showed the plane wobbling just feet above the water before impact and flames, while the Coast Guard also released footage of the burning aircraft.
The flight was carrying 10 passengers and a pilot from Seattle to Roche Harbor, and Kenmore said it would not speculate on the cause while cooperating with investigators.
The National Transportation Safety Board confirmed Friday that it is investigating the crash involving the U.S.'s largest seaplane airline.