The Coast Guard said it received a report of the crash around 3:11 pm (22:11 GMT) and dispatched helicopters and boats to scour the area. Local search and rescue officials were also on the scene.

“One deceased individual was recovered by crews on scene. Nine individuals remain unaccounted for, and a safety zone has been put into effect to help facilitate search efforts,” the coast guard said in a statement, adding that no cause for the crash had yet been determined.

The plane crashed while flying over the Pacific Ocean inlet of Puget Sound while on its way to Renton Municipal Airport near Seattle.

Flight tracking website Flight Radar 24 said it was monitoring reports of the crash, and that it had recorded the last signal from a 55 year old De Havilland Canada DHC 3 Otter a single engine propeller plane in the area at 3:08 pm local time at 100 feet (30.5 meters) of altitude.

Initially, the Coast Guard’s Pacific Northwest division tweeted that eight adults and one child were on board. It later tweeted an update that they were searching for 10 passengers.