A missing plane in Alaska that had 10 people on board Thursday, experienced a rapid loss in altitude and speed, prompting the Coast Guard to launch a search and rescue operation, officials said Friday.

A spokesperson for the U.S. Coast Guard said crews had not been able to fully open the plane and were continuing to search.

The plane was flying from the Alaskan coastal city of Unalakleet to another city along the Bering Sea coast, Nome—a journey that usually takes less than an hour.