Two planes carrying cruise ship tourists collide under unknown circumstances near Ketchikan town in Alaska.

Two seaplanes carrying cruise ship tourists have collided midair over southeastern Alaska, killing at least five and injuring 10, while one person is missing.

The accident occurred on Monday afternoon over waters about 40 kilometres northeast of Ketchikan town, said Petty Officer Jon-Paul Rios, a coastguard spokesperson.

The seaplanes collided under unknown circumstances, Allen Kenitzer, a spokesman of the Federal Aviation Administration (FAA) said in an email to the Associated Press news agency.

Weather conditions in the area on Monday included high overcast skies.

Seaplanes have pontoons mounted under the fuselage so they can land on water.

Local emergency responders worked with state and federal agencies and good Samaritan vessels to help rescue victims.

Cruise ship

The passengers were from the cruise ship Royal Princess and were on sightseeing flights.

The ship left Canada‘s Vancouver city on May 11 and was scheduled to arrive in the city of Anchorage in Alaska on Saturday.

“Our thoughts and prayers are with those who lost their lives and the families of those impacted by today’s accident. Princess Cruises is extending its full support to traveling companions of the guests involved,” Princess Cruises said in a statement.

The FAA and the National Transportation Safety Board are investigating the accident.

The Washington DC-based investigative team from the National Transportation Safety Board is expected to arrive in Ketchikan on Tuesday afternoon, agency spokesman Peter Knudson said.

He said board member Jennifer Homendy is also travelling with the so-called “Go Team”, which investigates major accidents.

Misty Fjords

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 480km south of Juneau, Alaska’s capital.

One of the aircraft involved was a de Havilland DHC-2 Beaver with five people on board and the other was a de Havilland Otter DHC-3 carrying 11 people, FAA spokesperson Allen Kenitzer said in an email message, citing information from local authorities.

The Ketchikan-based operator of the larger plane, Taquan Air, said its pilot and nine passengers were rescued and they were receiving medical attention, but one passenger’s fate remained unknown.

That group was returning from a sightseeing tour of Misty Fjords when the crash occurred, Taquan said in a statement.

A spokesperson for Taquan Air, the operator of the Otter, said the company had suspended operations while federal authorities investigate the deadly crash.

It is not the first time a major plane crash has occurred near Ketchikan, a popular tourist destination.

In June 2015, a pilot and eight passengers had died when a de Havilland DHC-3 Otter, operated by Promech Air Inc, crashed into mountainous terrain about 39km from Ketchikan.

The NTSB later determined that pilot error and lack of a formal safety programme were behind the crash.