4 dead, 2 missing, 10 hospitalized after midair collision over Alaska

"There are two people that we're still searching for at this time," Coast Guard Petty Officer Jon-Paul Rios told ABC News in an interview airing Tuesday on "Good Morning America."

"Our crews are out there searching diligently alongside our partner agencies and some good Samaritans," he added. "They've been searching throughout the day, by both air and by sea."

The deadly collision took place Monday afternoon in Coon Cove, Alaska, according to the Federal Aviation Administration. A de Havilland DHC-2 Beaver with five people on board and a de-Havilland Otter DHC-3 carrying 11 people clashed in midair "under unknown circumstances," the FAA said in a statement.

Ten people with injuries from the incident were taken to PeaceHealth Ketchikan Medical Center, according to hospital spokeswoman Mischa Chernick. Three of the patients are listed in serious condition, while seven are in fair condition, Chernick told ABC News.

Both planes were on sightseeing tours, carrying guests from the Royal Princess cruise ship, which was on a seven-day voyage that departed Vancouver on May 11 and was scheduled to arrive in Anchorage on Saturday, according to Princess Cruise Lines.

"We are incredibly distressed by the situation, and our thoughts and prayers are with those on board the planes and their families," the cruise line said in a statement. "Princess Cruises is extending its full support to traveling companions of the guests involved.

One of the planes was operated by Taquan Air, which said it has suspended all scheduled flights and is cooperating fully with investigators.

"We are devastated by this news and our hearts go out to our passengers and their families," the airline said in a statement.

The Coast Guard, the FAA and the National Transportation Safety Board are all investigating the incident.