"An MH-60 Jayhawk helicopter crew from Coast Guard Air Station Sitka located the wreckage at 2:37 p.m. and lowered two rescue swimmers who reported no survivors," the Coast Guard said in a statement.
The identities of those killed in the crash were not immediately released, but officials said there were six people on board, including the pilot.
The plane, a single-engine DeHavilland DHC-2 Beaver, took off from Misty Fjords National Monument and crashed around 11:20 a.m. in an area of steep, mountainous terrain near Ketchikan, about 300 miles southeast of Juneau, officials with the Federal Aviation Administration (FAA) and the National Transportation Safety Board (NTSB) told the Anchorage Daily News.
There was mist and light rain at the time of the crash, the Coast Guard said, along with 8 mph winds and visibility of two miles.
The five passengers on the flight were from the Holland America Line cruise ship, Nieuw Amsterdam, the company said in a statement.
"We can confirm that a float plane carrying five guests from Nieuw Amsterdam was involved in an accident in Ketchikan, and there are no survivors," the company tweeted. "It was an independent tour not sold by Holland America Line. Our thoughts and prayers are with the family and friends of the victims."
The Coast Guard, Alaska State Troopers, U.S. Forest Service, and the Ketchikan Volunteer Rescue Squad (KVRS) responded to the downed aircraft and a helicopter spotted the wreckage on a ridgeline, according to the Coast Guard. The aircraft was owned by Southeast Aviation LLC.
Ketchikan is a popular stop for cruise ships visiting Alaska, where passengers can take a variety of sightseeing trips while in port.
Popular among them are small plane flights to Misty Fjords National Monument, where visitors can see glacier valleys, snow-capped peaks, and lakes in the wilderness area.
In 2019, two sightseeing planes collided in midair near Ketchikan, killing six of the 16 people on board the two planes, the Daily News reported.
The NTSB is sending a crew to investigate the crash and the team expects to arrive on Friday. The FAA is also investigating.
The Associated Press contributed to this report.