An Australian cruise ship passenger has died after two sightseeing seaplanes collided in mid-air in Alaska.
America's National Transportation Safety Board has launched a search operation involving aircraft and multiple sea vessels.
Local authorities confirmed at least four people had been killed, while an Australian and a Canadian were still missing.
Three of the four victims are said to be American.
'We are devastated by today's incident and our hearts go out to our passengers and their families', a statement from flight operators Taquan Air said.
Sixteen people in total were on board the two aircraft, most were passengers on the Royal Princess cruise liner touring the region.
Cruise line Princess Cruises said two other guests, one Australian and one Canadian, are missing.
'All of us at Princess Cruises are deeply saddened by this tragic news and we are extending our full support to the investigating authorities as well as the travelling companions of the guests involved,' company spokesman Brian O'Connor said in a statement.
The Royal Princess, which can carry up to 3,600 people, was among four city-sized cruise ships in the tiny coastal community on Monday.
Earlier, the company confirmed that the pilot of a de Havilland DHC-2 Beaver and at least three passengers were killed in the collision with a de Havilland Otter DHC-3 yesterday.
The cause of the crash in relatively good weather, high overcast skies with light southeast winds was not known. The crash occurred about 13 kilometres from Ketchikan, near George Inlet.
The planes came down about three kilometres apart with some of the debris field on land. Their altitude wasn't immediately known
The collisions, 370 kilometres south of the Alaskan capital Juneau, where the water temperature is currently hovering around 10 degrees.
Four survivors were taken to Harborview Medical Centre in Seattle late last night.