By Rich McKay and Brad Brooks

(Reuters) -The U.S. Coast Guard in Alaska said on Friday that an “item of interest” had been found during the search operation looking for a small plane that suddenly lost altitude and went missing with 10 people on board the day before.

The Cessna 208B Grand Caravan aircraft carrying a pilot and nine adult passengers was reported missing en route from Unalakleet about 4 p.m. local time on Thursday, according to a dispatch posted on the website of the Alaska State Troopers in Nome, which is more than 500 miles (805 km) northwest of Anchorage.

The plane went missing about 12 miles (19 km) offshore over the icy waters of the Norton Sound, which is part of the Bering Sea, according to the Coast Guard.

Benjamin McIntyre-Coble, an officer with the Coast Guard in Alaska, said during a press briefing that “there has been some sort of item of interest” identified by an aircraft in the search efforts, but he had no details on what that item was.

McIntyre-Coble also said that the plane suffered a rapid loss of altitude and speed, according to radar data, but he could offer no details on what may have caused that. Weather was wintry and poor in the area where the plane suddenly dropped, officials said.

The plane was operated by Bering Air and was making a 150-mile trip from Unalakleet to Nome, a regularly scheduled commuter flight that traverses the Norton Sound. All on board were adults, officials said. Family of those on board have been notified, but no names have been released.

Clint Johnson, chief of the National Transportation Safety Board’s Alaska office, said during Friday’s press conference that the NTSB has begun its investigation, but that for now search and rescue operations were the focus.

The incident comes at a time of heightened scrutiny of air safety in the United States. NTSB investigators are probing two deadly crashes in recent days: the midair collision of a passenger jet and U.S. Army Black Hawk helicopter in Washington, D.C., that killed 67 people, and a medical jet crash in Philadelphia that killed seven.

The Nome Volunteer Fire Department was conducting a ground search for the missing plane, it said on its Facebook page, adding that a local hospital was on standby to receive casualties. It asked that local residents and families not form their own search parties due to poor weather and visibility.

(Reporting by Rich McKay in Atlanta and Brad Brooks in Colorado; Editing by Frank McGurty, Mark Porter and Marguerita Choy)

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