Mutiny Bay, Washington - One person was killed and nine people remained unaccounted for on Sunday after a float plane crashed off the coast of Washington state, the US Coast Guard said.

Per a press release, the US Coast Guard received a report of a crash at 3:11 PM on Sunday.

The crash involved a float plane that was en route to Renton Municipal Airport after departing from Friday Harbor. There were ten people on board, including a child.

The plane went down in Mutiny Bay off Whidbey Island, which is about halfway between Friday Harbor and Renton.

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An extensive search is underway, and consists of local first responders, four Coast Guard vessels, a rescue helicopter, and an aircraft.

Two Coast Guard vessels, Cutters Osprey and Blue Shark, continued the search overnight and, per the US Coast Guard's Pacific Northwest's Twitter posts, air patrols would resume at first light.

In their release, the Coast Guard said, "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 cause of the incident is unknown at this time," they added.

Float plans are a common sight around the scenic Pacific Ocean inlet Puget Sound. They have specialized platoons which allow them to land on water.