The US Coast Guard has confirmed that four people have died after two sightseeing planes crashed in mid-air in Alaska.
Searches are continuing for two people missing since the crash on Monday.
Ten other people were rescued and have been taken to hospital for treatment. The Coast guard said the extent of their injuries is unknown.
Officials said the crash happened at George Inlet near the city of Ketchikan, and involved two small float planes.
According to US media outlets, several of the passengers on board the planes were from a cruise ship.
In a statement to ABC News, Princess Cruise Lines said: "We are incredibly distressed by the situation, and our thoughts and prayers are with those onboard the planes and their families.
"Princess Cruises is extending its full support to traveling companions of the guests involved."
The search operation is being led by the US Coast Guard. A number of boats and a Jayhawk helicopter are involved in the search effort.
Coast Guard Captain Stephen White said: "In a remote area such as this, given our limited resources, we rely on our partner agencies and appreciate the support that good Samaritans have rendered to this point.
"With the loss of life in this case, we know that the impact to Alaska is immense and our thoughts are with the community here."
US transport authorities are set to investigate the cause of the crash.
