The US Coast Guard reports that a sightseeing plane crashed in southeast Alaska, killing all six passengers on board.

According to the Coast Guard and the Federal Aviation Administration, the plane's emergency warning beacon was activated late Thursday morning (local time) when it crashed near Ketchikan in the Misty Fjords National Monument.

The debris was discovered by Coast Guard crew members in the afternoon after a helicopter company reported seeing wreckage on a ridgeline in the search area.

A Coast Guard helicopter dropped two rescue swimmers on the scene, but there were no survivors, according to the service.

According to the company, the five passengers on the trip were from the Holland America Line cruise ship Nieuw Amsterdam.

Following the plane tragedy, the ship made a pit stop in Ketchikan on Thursday and postponed its afternoon departure.

Cruise ship passengers can enjoy a variety of sightseeing excursions while in port at Ketchikan, which is a popular stop for cruise ships visiting Alaska.