Anchorage: Two seaplanes collided in midair on Monday over south-eastern Alaska, killing at least four of those aboard, injuring 10 others and leaving three people missing, US Coast Guard and Federal Aviation Administration officials said.

A seaplane crash near Ketchikan, Alaska, in 2018. Credit:AP

The two aircraft went down over water about 40-48 kilometres north-east of Ketchikan, Coast Guard Petty Officer Jon-Paul Rios said.

The crash site, which the FAA said was at Coon Cove near George Inlet, lies in the vicinity of a popular tourist lodge that runs excursions to the nearby Misty Fjords National Monument, about 480 kilometres south of Juneau, Alaska's capital.

One of the aircraft was a de Havilland DHC-2 Beaver with five people aboard, and the other was a de Havilland Otter DHC-3 carrying 11 people, FAA spokesman Allen Kenitzer said.