At least 12 passengers and crew members were injured while travelling on a Cathay Pacific flight from San Francisco to Hong Kong yesterday when the plane hit "strong turbulence" as it passed over Japan. On arrival, the two injured crew members and six of the injured passengers were sent to Princess Margaret Hospital in Kwai Chung and North Lantau Hospital in Tung Chung. Of the eight, a stewardess was still in serious condition in hospital last night. She was earlier seen being taken to hospital with a neck brace and oxygen mask on. The other seven were released from hospital after treatment. Four other passengers had minor injuries that did not require hospital treatment. "It was even more intense than sitting on a roller coaster," said one of the passengers. "[The plane] was jolted for at least two minutes. I was thrown up very high." He said there was no broadcast or signal requiring passengers to fasten their seatbelts before the turbulence, which started very suddenly. He described how some passengers were thrown out of their seats and into the overhead lockers. The person in front of him hit the locker so hard that it was damaged, he said. Flight CX879 left San Francisco on Monday with 321 passengers and 21 crew aboard when the Boeing 747 unexpectedly ran into strong turbulence over Hokkaido at around 12.30pm, Cathay said. The plane landed at Chek Lap Kok airport at 6.26pm. Seven ambulances were waiting at the airport to take the injured to hospital, according to a photo posted on the Facebook page of a group of aviation enthusiasts. Cathay said the crew members had already begun treating the injured on board the plane and the airline would provide further support for them in Hong Kong. The Airport Authority said it had made the necessary arrangements to facilitate rescue efforts after the airline notified it of the accident. The Civil Aviation Department said it would send officers to look into the cause of the problem and would decide whether an investigation was necessary. The department also said it would assist an investigation into the incident to be spearheaded by the Japan Transport Safety Board.