The plane was on a shore excursion, sold through Holland America Line, when the accident happened about 20 miles northeast of Ketchikan, near Ella Lake.

There is official no word yet on the condition of those on the plane, but a private helicopter pilot reported to seeing plane wreckage against a cliff near the location it was believed to have gone down, the Alaska Department of Public Safety said.

The U.S. Coast Guard and local search and rescue teams are en route to the accident site. The National Transportation Safety Board said it is gathering information but does not have many details so far.

"We are incredibly distressed by this situation, and our thoughts and prayers are with those on board the plane and their families," Holland America said in a written statement.

The eight passengers were from the ms Westerdam, according to the statement. The Westerdam is sailing a seven-day Inside Passage cruise round-trip from Seattle. It departed Saturday.

Ian Gregor, with the Federal Aviation Administration, confirmed the aircraft was a DeHavilland DHC-3 Otter and that it crashed under unknown circumstances above Ella Lake.

(CNN)