Sixteen people aboard a U.S. passenger aircraft were injured Saturday morning after it ran into turbulence over Anchorage, Ala., while it was traveling from Washington D.C. to Narita, police and air transport authorities said, according to Kyodo news.

Turbulence hit the Boeing 747-400 United Airlines flight 897 at 10:55 a.m. local time, when the aircraft, carrying 264 people, was trying to descend to an altitude of 30,200 feet from 31,800 feet, according to the airport office of the Land, Infrastructure, Transport and Tourism Ministry.

The plane ran into turbulence at an altitude of 31,500 feet.

Later, the aircraft landed safely at Narita at around 3:45 p.m., according to the airport office.

Although the airline initially alerted fire crew members that 17 people were injured, it was later found that the number was 16, the authorities said.

The 16 people were rushed to hospitals by helicopters and other transportation means, police said.

The airliner departed from Dulles International Airport at around 2:40 a.m. Saturday, Japan time.

A 50-year-old university professor from Fukuoka who was aboard the flight told Kyodo News, "The aircraft was jolted vehemently over Alaska twice or so about seven hours before its arrival. Many passengers were tossed from their seats, bumping into the ceiling."

Since the aircraft is registered in the United States and the accident took place outside Japanese territorial airspace, U.S. authorities will look into the case.

The captain of the aircraft did not alert air traffic controllers at Narita airport of the accident or declare that the aircraft was in a state of emergency, and the controllers obtained the information by a call from Narita International Airport Corp., the authorities said.