ANCHORAGE, Alaska -- Dive teams plunged into the icy cold waters of a southeast Alaska inlet Tuesday, searching an area the size of 24 football fields for two cruise ship passengers missing after two sightseeing planes collided.
The Coast Guard has confirmed four fatalities in the collision Monday afternoon near Ketchikan, a popular destination for cruise ships in Alaska. Ten people, all Americans, were injured. The missing passengers were from Canada and Australia, Princess Cruises said.
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.
During port stops, visitors can shop in tourist stores or take part in several excursions, such as visiting an Alaska Native village, tour the backcountry, or visit a raptor center.
Another popular trip is flightseeing in Misty Fjords National Monument. Visitors marvel at the lakes, snowcapped peaks and glacier valleys in the wilderness area. Trips cost about $260 each.
The larger plane, a de Havilland Otter DHC-3 with 10 passengers and the pilot, was returning from Misty Fjord when it collided with another sightseeing plane, carrying four passengers from the same cruise ship and a pilot.
The cause of the crash in relatively good weather, high overcast skies with light southeast winds was not known. The crash occurred about eight miles (13 kilometers) from Ketchikan, near George Inlet. The planes came down about a mile and a half apart with some of the debris field on land. Their altitude wasn't immediately known.
The smaller plane, a de Havilland DHC-2 Beaver, was partially submerged in the shore of George Inlet after the single-engine plane overturned and hit some trees before crashing, according to Coast Guard Lt. Brian Dykens. The larger Otter landed in water and sank, he said.
Investigators from the National Transportation Safety Board were due to arrive later Tuesday.
Three others who died were among the five people aboard the Beaver, according to Coast Guard Lt. Brian Dykens. Princess Cruises in its release said two passengers and the pilot were among those killed in this plane.
Canadian officials said Tuesday that one of its citizens was among the dead. Global Affairs Canada expressed condolences but did not identify the person because of privacy reasons.
The smaller plane, which operated independently and not as an official excursion flight booked through the cruise ship, was owned by Mountain Air Service of Ketchikan, which didn't immediately return a call Tuesday.
The Beaver appears to have broken apart in midair, according to Jerry Kiffer, duty incident commander of the Ketchikan Volunteer Rescue Squad. He said the plane's tail and section of the fuselage were 900 feet (275 meters) from the aircraft's floats, which landed near shore.
After the crash, the 10 injured passengers were initially taken to a hospital in Ketchikan. Four patients were later transferred to Harborview Medical Center in Seattle, suffering various broken bones, spokeswoman Susan Gregg said.
Last summer, all 11 on board another Taquan Air flight survived when the 72-year-old pilot confused snow on a mountain with a body of water and crashed on a rocky mountainside on Prince of Wales Island near the southern tip of the Alaska Peninsula.
A pilot and eight cruise ship passengers died June 25, 2015, when a de Havilland DHC-3 Otter operated by Promech Air Inc. crashed into mountainous terrain about 24 miles (38 kilometers) from Ketchikan, also as it was returning from Misty Fjords.
The NTSB later determined that pilot error, the company's culture and lack of a formal safety program were among the causes of that crash. Taquan Air purchased the assets of Promech a year after the crash, and currently employs three pilots who worked for Promech, a company spokeswoman said.
The Royal Princess left Vancouver, British Columbia, on May 11 and was scheduled to arrive in Anchorage on Saturday.
"We are extending our full support to the investigating authorities as well as the traveling companions of the guests involved," the company said in a statement.